Automatic pool chlorinators take the daily chore of dosing chlorine out of your hands by metering 3-inch tablets into your water at a steady, adjustable rate. After comparing 15 of the most popular feeders, the Hayward CL2002S In-Line Automatic Chemical Feeder stands out as the best overall pick for its durable build, easy dial-based output control, and large tablet capacity. If you’re working with a tighter budget or an above-ground setup, the XtremepowerUS Inline Automatic Chlorinator delivers the same core function at a lower cost, while the Pentair R171016 Rainbow 300 is the strongest premium choice for larger pools. The main tradeoffs in this category come down to inline versus offline installation, tablet capacity, and whether you pay more for the Hayward and Pentair name or save with a compatible third-party unit. Read on for the full breakdown of all 15 models.
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Key Takeaways
- Name-brand feeders from Hayward and Pentair dominated the top spots because of their thicker housings, replacement-part availability, and reliability over multiple seasons, while compatible clones from XtremepowerUS, MAYGO, and U.S. Pool Supply won on price.
- Inline models like the Hayward CL2002S and Rainbow 320 need to be plumbed into your return line, so they suit new builds and renovations; offline feeders like the CL220EF retrofit onto existing plumbing without cutting pipes.
- A 9-pound tablet capacity was the practical sweet spot in this comparison — smaller units need refilling every week or two, while 9-pound feeders stretch refills to three or more weeks for typical residential pools.
- Dial-based output control varied widely in precision: Hayward and Pentair valves offered consistent low settings, which matters most for small pools and spas where over-chlorination happens fast.
- Several third-party units (R171096, R171016, and MAYGO MG200) are direct replacements for specific Rainbow and Hayward models, so buyers should match their existing plumbing threads before ordering to avoid returns.
| Hayward CL100 Automatic Chlorine Feeder |  | Best for Above-Ground Pools and Spas | Tablet Size: 3-inch Trichlor tablets | Power Source: AC/DC | Flow Rate: 50 gpm | VIEW LATEST PRICE | See Our Full Breakdown |
| R171096 Automatic In-Line Pool Chlorinator – Compatible with Rainbow 320 |  | Best Value Replacement | Brand: E-cowlboy | Compatibility: Pentair R171096 / Rainbow 320 | Material: ABS plastic | VIEW LATEST PRICE | See Our Full Breakdown |
| XtremepowerUS Inline Automatic Chlorinator for Above Ground and Inground Pools |  | Best for New Permanent Installations | Tablet Size: 3-inch slow-dissolve tablets | Tank Capacity: 9 lbs | Material: UV-resistant ABS / heavy-duty resin | VIEW LATEST PRICE | See Our Full Breakdown |
| CL220 Offline Chlorinator for Swimming Pools and Ponds |  | Best Budget Offline Option | Model: CL220 | Compatibility: Hayward CL220 replacement | Capacity: 9 lbs of chlorine tablets | VIEW LATEST PRICE | See Our Full Breakdown |
| Hayward CL220EF Off-Line Chemical Feeder, 9 lbs Capacity |  | Best Premium Offline Feeder | Capacity: 9 lbs | Type: Off-line chemical feeder | Cover: Easy Lok threaded cover | VIEW LATEST PRICE | See Our Full Breakdown |
| R171016 Pool Chlorinator Compatible with Pentair Rainbow 300 |  | Best Budget Replacement for Rainbow 300 Owners | Brand: Miory | Model Number: R171016 | Compatibility: Pentair Rainbow 300 offline chlorinator | VIEW LATEST PRICE | See Our Full Breakdown |
| Hydrotools by Swimline 8750 In-Line Automatic Chlorine Feeder |  | Best Heavy-Duty In-Line Feeder | Brand: Hydrotools by Swimline | Capacity: 9.0 lbs of tablets | Type: In-line automatic chlorine feeder | VIEW LATEST PRICE | See Our Full Breakdown |
| Hayward CL2002S In-Line Automatic Chemical Feeder |  | Best Premium Name-Brand Pick | Brand: Hayward | Type: In-line automatic chemical feeder | Compatible Chemicals: Trichlor or bromine tablets and sticks | VIEW LATEST PRICE | See Our Full Breakdown |
| Pentair R171016 Rainbow 300 Automatic Pool and Spa Feeder |  | Best for Spas and Safety-Minded Buyers | Brand: Pentair | Model Number: R171016 | Sanitizer Type: Chlorine / Bromine | VIEW LATEST PRICE | See Our Full Breakdown |
| U.S. Pool Supply Professional In-Line Automatic Pool Chlorine Feeder, 9 lb Capacity |  | Best for Above-Ground Pool Owners | Brand: U.S. Pool Supply | Model Number: USP CF-478 | Chemical Capacity: 9 lbs (4 kg) | VIEW LATEST PRICE | See Our Full Breakdown |
| XtremepowerUS Off-Line Automatic Pool Chlorinator Feeder for Above Ground & In-Ground Pools |  | Best Budget Off-Line Pick | Capacity: 9 lbs of 3-inch tablets | Type: Off-line automatic chlorinator | Compatible Tablets: 3-inch trichlor chlorine or bromine tablets | VIEW LATEST PRICE | See Our Full Breakdown |
| MAYGO MG200 Inline Automatic Pool Chlorinator, 1-1/2″ Internal Thread Connection (9LB) |  | Best Replacement for a Hayward CL200 | Brand: MAYGO | Model: MG200 | Connection: 1-1/2″ internal thread (2-1/2″ external) | VIEW LATEST PRICE | See Our Full Breakdown |
| Pentair R171096 Rainbow 320 Automatic In-Line Chlorine/Bromine Feeder |  | Best Premium Permanent Installation | Brand: Pentair | Model: R171096 Rainbow 320 | Installation: In-line, permanent | VIEW LATEST PRICE | See Our Full Breakdown |
| Hayward Automatic Chlorine Chemical Feeder for In-Ground and Above Ground Pools |  | Best Overall | Brand: Hayward | Compatibility: In-ground and above ground pools | Tablet Size: Large or small slow-dissolving tablets | VIEW LATEST PRICE | See Our Full Breakdown |
| Hayward CL200EF In-Line Automatic Chlorine Feeder for In-Ground Swimming Pools |  | Best for In-Ground Retrofit | Brand: Hayward | Model: CL200EF | Capacity: Up to 9 lbs of chlorine tablets | VIEW LATEST PRICE | See Our Full Breakdown |
| automatic pool chlorinator | Brand | Material | Compatibility |
|---|---|---|---|
| Hayward CL100 Automatic Chlori | — | Corrosion-proof plastic | — |
| R171096 Automatic In-Line Pool | E-cowlboy | ABS plastic | Pentair R171096 / Rainbow 320 |
| XtremepowerUS Inline Automatic | — | UV-resistant ABS / heavy-duty resin | Hayward CL200 |
| CL220 Offline Chlorinator for | — | Thickened ABS | Hayward CL220 replacement |
| Hayward CL220EF Off-Line Chemi | — | — | Fits off-line to most PVC plumbing |
| R171016 Pool Chlorinator Compa | Miory | — | Pentair Rainbow 300 offline chlorinator |
| Hydrotools by Swimline 8750 In | Hydrotools by Swimline | Commercial-grade double-reinforced thermoplastic | — |
| Hayward CL2002S In-Line Automa | Hayward | — | — |
| Pentair R171016 Rainbow 300 Au | Pentair | — | — |
| U.S. Pool Supply Professional | U.S. Pool Supply | Oxidation-resistant ABS plastic | — |
| XtremepowerUS Off-Line Automat | — | Heavy-duty resin | Above ground and small in-ground pools |
| MAYGO MG200 Inline Automatic P | MAYGO | ABS with EPDM O-ring seal | — |
| Pentair R171096 Rainbow 320 Au | Pentair | — | Chlorine and bromine |
| Hayward Automatic Chlorine Che | Hayward | — | In-ground and above ground pools |
| Hayward CL200EF In-Line Automa | Hayward | — | — |
More Details on Our Top Picks
Hayward CL100 Automatic Chlorine Feeder
The Hayward CL100 earns its place as the go-to feeder for smaller above-ground setups because it was purpose-built for them, unlike the bigger in-line units like the XtremepowerUS inline model, which are designed around permanent return-line plumbing. Its corrosion-proof housing and dial control valve keep chlorine output predictable, and the Easy-Lok threaded cover makes refills a one-person job without wrestling with stuck lids. Compared with the CL220EF, this unit is lighter and far less demanding to install — a genuine DIY afternoon rather than a plumbing project. The tradeoff is capacity and flexibility: it accepts only 3-inch Trichlor tablets, so anyone hoping to run bromine or smaller tabs needs to look elsewhere. It also depends entirely on a compatible pump and filter to function, which rules out setups with weak or intermittent circulation.
Pros:- Corrosion-proof, durable construction holds up to constant chemical exposure
- Dial control valve makes feed-rate adjustments simple and repeatable
- Easy-Lok threaded cover with finger-release catch for safe refills
- Straightforward installation that doesn’t require professional plumbing
Cons:- Only accepts 3-inch tablets, limiting chemical flexibility
- Requires a compatible pump and filter system, so weak circulation setups are out of luck
Best for: Owners of above-ground pools or spas who want a brand-name, corrosion-proof feeder with simple DIY installation
Not ideal for: In-ground pool owners or anyone wanting bromine support and large tablet capacity — this unit is sized and specced for small circulating systems only
- Tablet Size:3-inch Trichlor tablets
- Power Source:AC/DC
- Flow Rate:50 gpm
- Material:Corrosion-proof plastic
- Pool Type:Above ground pools and spas
- Dimensions:16″L x 8″W x 8″H
- Weight:4 ounces
Our verdict“This is the pick for above-ground pool and spa owners who want Hayward reliability without the plumbing complexity of an in-line feeder.”
R171096 Automatic In-Line Pool Chlorinator – Compatible with Rainbow 320
This E-cowlboy feeder makes the list because it solves a specific, expensive problem: replacing a failed Rainbow 320 without paying OEM pricing for the Pentair R171096 itself. The leak-proof dual O-ring seals are actually an upgrade over what many originals shipped with, and the 11-large-tablet capacity covers pools from 6,500 to 70,000 gallons — a wider range than the Hayward CL100 can touch. The included 2-inch slip fittings with 1.5-inch adapters mean most existing plumbing lines up without a hardware-store run. The honest tradeoff: this is a replacement part, not a fresh-install champion. If your plumbing wasn’t originally configured for an in-line feeder, expect cutting and gluing PVC — at which point a purpose-built unit like the Hydrotools 8750 may involve less guesswork. Documentation is also thinner than OEM standards.
Pros:- Upgraded dual O-ring seals improve leak resistance over many original units
- Huge tablet capacity handles pools from 6,500 to 70,000 gallons
- Includes 2″ slip fittings and 1.5″ adapters for broad plumbing compatibility
- Fully enclosed design keeps tablets safely away from children and pets
Cons:- Existing lines may need plumbing modifications to accept an in-line feeder
- Manuals and support don’t match OEM documentation quality
Best for: Budget-conscious owners of an existing Rainbow 320 setup who need a direct, low-cost replacement with upgraded seals
Not ideal for: First-time chlorinator buyers starting from scratch — this is built as a drop-in replacement, not a turnkey new installation
- Brand:E-cowlboy
- Compatibility:Pentair R171096 / Rainbow 320
- Material:ABS plastic
- Tablet Capacity:11 large or 98 small tablets
- Flow Control:Adjustable valve
- Pool Size Range:6,500–70,000 gallons
- Fittings:2″ PVC slip with 1.5″ adapters
- Warranty:12-month warranty, 30-day money-back guarantee
Our verdict“A smart money-saving swap for a worn-out Rainbow 320, as long as your plumbing is already compatible.”
XtremepowerUS Inline Automatic Chlorinator for Above Ground and Inground Pools
For anyone building or replumbing a pool system from scratch, this XtremepowerUS inline feeder is the strongest fit in this batch because it’s designed to live permanently in the return line after the filter and heater — the ideal position for steady, even chlorination. Its 9 lb tablet capacity rivals the CL220EF while supporting both chlorine and bromine, and the UV-resistant ABS body matters more here than it sounds: units sitting in pump-house sunlight crack and weep after a few seasons. Compared with the CL100, you get dramatically more capacity and dual-chemical support, but you pay for it in installation effort — expect pipe cutting and gluing, not a screw-on hookup. The dial valve lets you trim output so you’re not over-dosing and burning through tablets, which adds up to real chemical savings over a summer.
Pros:- 9 lb tablet capacity means refills are rare, not weekly
- Dial control valve prevents over-chlorination and stretches chemical budgets
- UV-resistant ABS and heavy-duty resin survive sun and chemical exposure
- Supports both chlorine and bromine tablets
Cons:- Requires cutting into the return line, making installation a real plumbing job
- Tablets sold separately, so initial cost understates total investment
Best for: Owners planning a permanent in-line installation on an above-ground or small in-ground pool who want large capacity and chlorine-or-bromine flexibility
Not ideal for: Renters or anyone unwilling to cut into return-line plumbing — this unit cannot simply be dropped into an existing hose setup
- Tablet Size:3-inch slow-dissolve tablets
- Tank Capacity:9 lbs
- Material:UV-resistant ABS / heavy-duty resin
- Installation:In-line, after filter and heater
- Compatibility:Hayward CL200
- Pool Type:Above ground or small in-ground pools
- Chemicals:Chlorine or bromine tablets (sold separately)
Our verdict“The right choice if you’re already opening the plumbing and want a high-capacity, dual-chemical feeder for the long haul.”
CL220 Offline Chlorinator for Swimming Pools and Ponds
This CL220-compatible offline feeder occupies a useful middle ground: it delivers the 9 lb capacity and 360° adjustable flow knob of pricier units like the Hayward CL220EF at a noticeably lower price, and it even extends to pond use, which most pool-only feeders never address. The full-turn flow control gives finer dosing granularity than the simple dial on the CL100, and the complete installation accessory kit spares you the piecemeal fittings hunt. But two things hold it back from a higher ranking. Offline installation still means tapping into existing lines with feeder hoses, and the documentation quality is genuinely suspect — translation errors in the product materials suggest you’ll be leaning on instinct and online guides during setup. If you’re comfortable with that, the savings are real.
Pros:- 9 lb tablet capacity keeps refill trips to a minimum
- 360° flow knob allows precise chlorine dosing adjustments
- Thickened ABS construction resists cracking under chemical exposure
- Complete installation accessory kit included out of the box
Cons:- Documentation contains translation errors, making setup harder than it should be
- Offline installation still requires tapping into existing pool plumbing
Best for: Handy DIY owners and pond keepers who want CL220-style capacity and don’t mind thin documentation in exchange for a lower price
Not ideal for: First-time installers who expect clear manuals — the rough documentation makes an already fiddly offline install harder
- Model:CL220
- Compatibility:Hayward CL220 replacement
- Capacity:9 lbs of chlorine tablets
- Material:Thickened ABS
- Flow Control:360° adjustable knob
- Type:Offline chlorinator
- Safety Feature:Safety unlock button on lid
Our verdict“A capable CL220-style feeder at a budget price, best for confident DIYers who won’t miss polished instructions.”
Hayward CL220EF Off-Line Chemical Feeder, 9 lbs Capacity
The Hayward CL220EF is the premium pick for retrofit situations: when you can’t or don’t want to cut your return line for an in-line unit like the XtremepowerUS feeder, an off-line feeder taps into existing PVC with hoses and becomes the cleanest path to automated chlorination. Hayward’s build quality is the real argument here — the fully enclosed system prevents escaping fumes and needs no special venting, which cheaper clones like the budget CL220 unit can’t always claim. The Easy Lok threaded cover is genuinely one-handed friendly, and the 9 lb capacity matches the best in this roundup. The cost of that quality is literal: this is the pricier route, and off-line installation still means additional plumbing work that a floater or the simple CL100 avoids entirely. You’re paying for durability and peace of mind, not convenience.
Pros:- Fully enclosed system prevents fume escape without any special venting
- Easy Lok threaded cover makes tablet refills safe and convenient
- 9 lb capacity keeps maintenance infrequent
- Fits off-line to most PVC plumbing for easier retrofits
Cons:- Off-line installation still requires additional plumbing work and fittings
- Priced well above comparable third-party offline feeders
Best for: In-ground pool owners who want to add automated chlorination without cutting into their main return line, and prefer trusted brand engineering
Not ideal for: Casual above-ground pool owners — the premium price and plumbing requirements are overkill when a simpler feeder would do the job
- Capacity:9 lbs
- Type:Off-line chemical feeder
- Cover:Easy Lok threaded cover
- Venting:None required
- Compatibility:Fits off-line to most PVC plumbing
Our verdict“The premium offline choice for in-ground pool owners who value Hayward build quality and a no-venting, fume-free design over bargain pricing.”
R171016 Pool Chlorinator Compatible with Pentair Rainbow 300
This option makes the most sense for anyone who already owns a Pentair Rainbow 300 and needs a like-for-like swap without paying OEM pricing. Miory kept the same offline footprint but upgraded the parts that usually fail first: the high-density control valve resists the clogging and corrosion that plague aging feeders, and the wider leak-proof base addresses the gasket seepage common on well-worn originals. Compared with the Pentair R171016 Rainbow 300 elsewhere in this roundup, you get installation accessories in the box rather than buying unions separately. The tradeoff is that this is an offline unit, so it still needs the hose-tap plumbing loop, and the valve and O-rings demand regular lubrication and cleaning to keep the improved sealing intact over multiple seasons.
Pros:- Direct drop-in fit for Pentair Rainbow 300 systems
- Upgraded control valve resists clogging, corrosion, and leaks
- Handles pools up to 72,000 gallons
- Includes all installation accessories out of the box
Cons:- O-rings and control valve need routine lubrication and cleaning to last
- Offline design still requires plumbing into the return line
Best for: Budget-conscious owners of an existing Rainbow 300 system who want a direct-fit replacement with upgraded seals
Not ideal for: Buyers starting from scratch with no existing plumbing, since offline installation still requires tapping into the return line
- Brand:Miory
- Model Number:R171016
- Compatibility:Pentair Rainbow 300 offline chlorinator
- Type:Offline chlorine feeder
- Treatment Capacity:Up to 72,000 gallons
- Suitable For:Above-ground pools, in-ground pools, spas
- Items Included:12 (feeder plus installation accessories)
Our verdict“If your Rainbow 300 has seen better days, this is the most economical way to restore automatic chlorination without re-plumbing anything.”
Hydrotools by Swimline 8750 In-Line Automatic Chlorine Feeder
Where the U.S. Pool Supply CF-478 targets above-ground setups, this Hydrotools unit is built for continuous duty on larger plumbed systems. Its 9 lb tablet capacity means fewer refills across a long swim season, and the commercial-grade double-reinforced thermoplastic holds up against UV exposure and corrosive tablet fumes better than standard housings. The standout convenience is that it installs as a drop-in replacement for Hayward and Pentair plumbing, so if you are swapping a failed Hayward CL200-series unit, no special tools are needed. Bromine support also makes it flexible for spa owners. The catch is structural: because it is strictly in-line, it cannot work on pools without a plumbed pump-and-filter loop, and unlike some rivals, tablets arrive separately.
Pros:- Drop-in compatibility with Hayward and Pentair plumbing, no special tools needed
- Large 9 lb capacity reduces refill frequency
- Commercial-grade double-reinforced thermoplastic resists UV and corrosion
- Adjustable output dial plus bromine compatibility
Cons:- Chlorine tablets sold separately
- Only works on pools with existing pump and filter plumbing
Best for: Owners of large above-ground or in-ground pools with existing plumbing who want long intervals between refills
Not ideal for: Anyone with an un-plumbed or inflatable pool, since this feeder only functions inline with a pump and filter system
- Brand:Hydrotools by Swimline
- Capacity:9.0 lbs of tablets
- Type:In-line automatic chlorine feeder
- Installation:Drop-in replacement for Hayward and Pentair plumbing
- Material:Commercial-grade double-reinforced thermoplastic
- Chemical Compatibility:Chlorine and bromine
- Pool Type:Above-ground and in-ground
- Adjustable Output:Yes
Our verdict“This is the workhorse pick for plumbed pools that burn through tablets fast and need a feeder that survives seasons of chemical exposure.”
Hayward CL2002S In-Line Automatic Chemical Feeder
This is the option for buyers who prioritize brand-name engineering and long-term parts availability. Hayward pairs a corrosion-proof ABS body with a Viton seal, a combination that outlasts the generic thermoplastic builds found on the XtremepowerUS and MAYGO feeders in this guide. The Easy-Lok threaded cover with finger-release catch is a genuine safety upgrade — it lets you load Trichlor or bromine tablets quickly without fighting a stuck, chemically-welded lid, a common frustration on cheaper units. With 2-inch ports handling 50 to 90 gpm, it suits higher-flow in-ground systems where smaller feeders bottleneck. The tradeoffs are real though: the in-line design may need professional plumbing on retrofits, and it strictly requires slow-dissolving Trichlor or bromine tablets — nothing else.
Pros:- Corrosion-proof ABS body with Viton seal for extended lifespan
- Easy-Lok threaded cover with finger-release catch for safe tablet loading
- 2-inch ports support 50 to 90 gpm flow rates
- Genuine Hayward parts and service network widely available
Cons:- In-line plumbing may require professional installation on existing setups
- Only accepts slow-dissolving Trichlor or bromine tablets and sticks
Best for: In-ground pool owners who want a proven OEM feeder with wide parts availability and high-flow compatibility
Not ideal for: DIYers retrofitting an existing pool without plumbing experience, since in-line installation can require a professional
- Brand:Hayward
- Type:In-line automatic chemical feeder
- Compatible Chemicals:Trichlor or bromine tablets and sticks
- Port Size:2-inch inlet and outlet
- Flow Rate Range:50 to 90 gpm
- Body Material:Corrosion-proof ABS
- Seal Material:Viton
- Suitable For:Above-ground and in-ground pools and spas
Our verdict“If you plan to keep your pool for a decade and want a feeder you can always find replacement parts for, the CL2002S justifies its premium positioning.”
Pentair R171016 Rainbow 300 Automatic Pool and Spa Feeder
Compared with the Miory R171016, this is the original OEM Rainbow 300, and its strongest argument is safety certification: it is NSF listed, which matters for commercial settings, renters, or anyone who wants third-party verification of materials and construction. The fully enclosed system contains sanitizer gases rather than venting them poolside, and it needs no special venting during installation — a genuine simplification over vented feeder designs. It handles both chlorine and bromine, making it a natural fit for spa owners running bromine, where many budget feeders fall short. The tradeoff is at unboxing: unions are not included, so unlike the Miory clone that bundles everything, you will make a separate hardware purchase, and offline installation still involves tapping into your return plumbing.
Pros:- Fully enclosed system prevents escaping sanitizer gases
- No special venting required during installation
- NSF listed for safety and material quality
- Works with both chlorine and bromine sanitizers
Cons:- Unions not included and must be purchased separately
- Offline installation may require additional plumbing work
Best for: Spa owners and safety-conscious or commercial buyers who want an NSF-listed, fully enclosed feeder
Not ideal for: Handy buyers on a tight budget, since the Miory R171016 offers a similar design with included accessories at lower cost
- Brand:Pentair
- Model Number:R171016
- Sanitizer Type:Chlorine / Bromine
- Installation Type:Off-line
- NSF Listed:Yes
- Unions Included:No
- Product Dimensions:14.75 x 22.25 x 23 inches
- Item Weight:3 lbs
Our verdict“This is the pick when certification and gas containment matter more than saving a few dollars on accessories.”
U.S. Pool Supply Professional In-Line Automatic Pool Chlorine Feeder, 9 lb Capacity
This feeder is purpose-built for the above-ground crowd, and that focus pays off in the details. It is compatible with the Hayward CL200 chlorinator, so it slots into an existing Hayward plumbing layout, yet it adds a feature the CL2002S lacks at this price: a transparent easy-lock cover that lets you check remaining tablets at a glance instead of opening a pressurized chamber. The included lid wrench sounds minor but solves one of the most annoying failure points on budget feeders — a cover chemically fused shut after a season of tablet fumes. With a 9 lb capacity it matches the Hydrotools 8750 for refill intervals, though its ABS build is lighter-duty than Hydrotools’ reinforced thermoplastic. Remember that tablets are not included, so budget for your first season of Trichlor separately.
Pros:- Transparent lid lets you monitor chemical levels without opening the chamber
- 9 lb capacity minimizes refill frequency
- Oxidation-resistant ABS body extends service life
- Includes installation accessories, instructions, and a lid wrench
Cons:- Chlorine tablets and sticks not included
- Lighter-duty construction than commercial-grade in-line feeders
Best for: Above-ground pool owners who want CL200 compatibility, a viewable chemical level, and a complete accessory kit at a moderate price
Not ideal for: Owners of large in-ground pools with high flow demands, who will be better served by the Hayward CL2002S or Hydrotools 8750
- Brand:U.S. Pool Supply
- Model Number:USP CF-478
- Chemical Capacity:9 lbs (4 kg)
- Material:Oxidation-resistant ABS plastic
- Compatible With:Hayward CL200 chlorinator
- Pool Type:Above-ground swimming pools
- Chemicals:Trichlor chlorine or bromine tablets and sticks
- Includes:Installation accessories, instruction guide, lid wrench
Our verdict“For above-ground pools, the viewable lid, included wrench, and Hayward CL200 compatibility make this the easiest ownership experience in the lineup.”
XtremepowerUS Off-Line Automatic Pool Chlorinator Feeder for Above Ground & In-Ground Pools
For pool owners who want automatic chlorination without cutting into their main plumbing, this off-line feeder from XtremepowerUS keeps things simple and affordable. The 9 lb tablet chamber means fewer refill trips than smaller units, and the dial control valve lets you tune the feed rate as seasons and bather loads change. Compared with the Hayward CL200EF, which is built strictly for in-ground circulation systems, this unit’s off-line design and included installation kit make it far more approachable for above ground pool setups. The tradeoff is fit and finish: the resin body feels less refined than Hayward’s ABS housings, and you still need to tap into existing piping, so it isn’t a true plug-and-play solution.
Pros:- Large 9 lb tablet capacity cuts refill frequency
- Adjustable dial valve for tuning chlorine feed
- Off-line installation restricts main water flow less
- Installation kit included, unlike some pricier rivals
Cons:- Chlorine tablets sold separately
- Still requires plumbing into existing piping
- Resin construction feels less durable than Hayward or Pentair housings
Best for: Above ground pool owners on a budget who want big capacity without hiring a plumber
Not ideal for: Owners of large in-ground pools wanting a permanent, polished installation — the resin build and generic fittings are better suited to lighter duty
- Capacity:9 lbs of 3-inch tablets
- Type:Off-line automatic chlorinator
- Compatible Tablets:3-inch trichlor chlorine or bromine tablets
- Material:Heavy-duty resin
- Compatibility:Above ground and small in-ground pools
- Includes:Installation kit
Our verdict“A sensible low-cost entry point for above ground pools, as long as you’re comfortable doing your own plumbing hookup.”
MAYGO MG200 Inline Automatic Pool Chlorinator, 1-1/2″ Internal Thread Connection (9LB)
If your existing Hayward CL200 has cracked or its seal has given up, the MAYGO MG200 is a direct replacement that fixes the original’s known weak points. The ABS body resists cracking better than aged OEM units, and the EPDM O-ring keeps chlorine fumes from escaping around the lid. Coverage up to 41,000 gallons means it can handle far larger pools than the typical above ground unit like the XtremepowerUS off-line model. The catch is the threading: the external thread doesn’t match CL200 fittings, so you’ll need an internal spiral connector, and the lid can’t be removed until air pressure is released — an extra step every refill.
Pros:- ABS construction resists cracking better than the original CL200
- 360-degree adjustable knob for precise feed control
- Leak-proof EPDM O-ring blocks chlorine odor
- 9 lb capacity treats pools up to 41,000 gallons
Cons:- External thread not compatible with CL200 fittings — requires an internal spiral connector
- Lid removal requires releasing air pressure first
- Screw-in connection limits flexibility versus slip-fit units like the Pentair Rainbow 320
Best for: Owners of a failed Hayward CL200 who want a like-for-like swap with upgraded materials
Not ideal for: Anyone expecting a drop-in thread match — the connector mismatch means an extra fitting purchase and some fiddling
- Brand:MAYGO
- Model:MG200
- Connection:1-1/2″ internal thread (2-1/2″ external)
- Capacity:9 lb of chlorine tablets
- Coverage:Up to 41,000 gallons
- Material:ABS with EPDM O-ring seal
- Replaces:Hayward CL200
- Weight:4 lbs (1.82 kg)
Our verdict“A smart repair-path purchase for CL200 owners, provided you account for the connector mismatch before install day.”
Pentair R171096 Rainbow 320 Automatic In-Line Chlorine/Bromine Feeder
The Pentair Rainbow 320 is the pick for pool owners building or replumbing for the long haul. Unlike the MAYGO MG200, which is a screw-in replacement part, this is a permanent in-line feeder that gets plumbed directly into your return line, with slip fittings and adapters covering both 2″ and 1-1/2″ pipe. The 11 large or 98 small tablet capacity edges out every 9 lb competitor here, and the fact that it needs no special venting simplifies the install considerably. The tradeoffs are real, though: unions aren’t included, so budget for them, and cutting into return line plumbing usually means professional installation for most owners.
Pros:- Permanent in-line design suits new or existing pools and spas
- No special venting required
- Largest capacity in this lineup — 11 large or 98 small tablets
- Adapters included for 2″ and 1-1/2″ plumbing
Cons:- Unions not included, adding cost and complexity
- Requires permanent plumbing work that may need a pro
- Higher upfront investment than budget feeders
Best for: Pool owners doing new construction or a major replumb who want a set-and-forget feeder that lasts decades
Not ideal for: Above ground pool owners or anyone unwilling to cut into permanent plumbing — an off-line unit like the XtremepowerUS is the easier route
- Brand:Pentair
- Model:R171096 Rainbow 320
- Installation:In-line, permanent
- Fittings:2″ slip PVC with 1-1/2″ adapters
- Tablet Capacity:11 large or 98 small tablets
- Compatibility:Chlorine and bromine
- Warranty:1-year
Our verdict“The feeder to buy when you’re plumbing once and never want to think about sanitization hardware again.”
Hayward Automatic Chlorine Chemical Feeder for In-Ground and Above Ground Pools
This Hayward automatic feeder earns the top spot because it removes the most common frustrations of the category. The Easy-Lok threaded cover with finger-release catch solves the stuck-lid problem that plagues cheaper feeders, and the Viton seal outlasts the standard O-rings found on units like the MAYGO MG200, standing up better to concentrated chlorine exposure. Flexibility is the other strength: it accepts both large and small slow-dissolve tablets and works on in-ground and above ground pools alike, where most rivals specialize in one or the other. The dial valve makes feed adjustments a quick twist. The main limitation is that it demands slow-dissolving tablets — fast-dissolving tabs will overdose the water.
Pros:- Works with both in-ground and above ground pools
- Easy-Lok threaded cover with finger-release catch for safe access
- Viton seal resists chemical degradation longer than standard O-rings
- Dial valve simplifies feed-rate adjustment
Cons:- Requires slow-dissolving tablets for correct operation
- No plumbing adapters included the way Pentair includes them
- Premium name-brand pricing versus budget feeders
Best for: Owners who want one dependable, name-brand feeder that works across pool types with minimal maintenance drama
Not ideal for: Buyers who want to use whatever tablets are cheapest — fast-dissolving tablets will not feed properly in this unit
- Brand:Hayward
- Compatibility:In-ground and above ground pools
- Tablet Size:Large or small slow-dissolving tablets
- Feed Control:Dial control valve
- Cover:Easy-Lok threaded cover with finger-release catch
- Body Material:ABS
- Seal Material:Viton
Our verdict“The safest all-around choice if you want proven hardware and painless refills rather than the lowest price.”
Hayward CL200EF In-Line Automatic Chlorine Feeder for In-Ground Swimming Pools
Where the Pentair Rainbow 320 assumes you’re doing permanent plumbing work, the Hayward CL200EF is designed to bolt into an existing in-ground circulation system with minimal disruption. Its 9 lb tablet chamber stretches the interval between refills, and the adjustable control dial lets you dial sanitizer output up for summer parties and back down for the off-season. The corrosion-resistant housing is built for years of constant chlorine exposure, matching Hayward’s reputation for durability seen in the standard Hayward feeder above. The tradeoff: it’s strictly an offline configuration, so if your plumbing isn’t set up for a bypass loop, professional installation is likely on the table.
Pros:- 9 lb tablet capacity minimizes refill frequency
- Adjustable dial for precise sanitizer output
- Chemical- and corrosion-resistant housing
- Integrates with many existing in-ground circulation systems
Cons:- Offline installation requires compatible plumbing
- Professional installation may be needed for proper integration
- In-ground only — no above ground flexibility like the standard Hayward feeder
Best for: In-ground pool owners with compatible plumbing who want to add automatic chlorination without replumbing the whole system
Not ideal for: Above ground pool owners or those without a bypass-ready setup — the offline-only design limits where it can go
- Brand:Hayward
- Model:CL200EF
- Capacity:Up to 9 lbs of chlorine tablets
- Installation Type:Offline plumbing configuration
- Pool Type:In-ground swimming pools
- Control:Adjustable control dial
- Construction:Chemical-resistant, corrosion-resistant housing
Our verdict“The right pick when your in-ground system is ready for a bypass feeder and you want Hayward reliability without a full replumb.”
How We Picked
I evaluated each chlorinator against the criteria that actually change the ownership experience: installation flexibility (inline versus offline, compatibility with existing plumbing), tablet capacity and how long a single fill lasts, output control precision at low settings, housing durability under constant chlorine exposure and sunlight, and long-term serviceability — whether seals, lids, and valves are replaceable years from now. I also weighed brand track record, since a feeder that cracks after two seasons is a poor value no matter the upfront savings.
The ranking logic favors models that balance all five criteria well rather than excelling at one. That’s why name-brand Hayward and Pentair units sit near the top despite their higher cost: their parts availability and build quality lower the total cost of ownership. Value picks from XtremepowerUS, Hydrotools, and U.S. Pool Supply ranked high where they matched the big brands on capacity and function, and I flagged every unit whose threading, capacity, or control design limits it to a specific buyer type so you can quickly rule out the wrong fit.
Factors to Consider When Choosing Automatic Pool Chlorinators
Before you settle on a specific feeder, it helps to understand the decisions that shape everything downstream — your plumbing, your maintenance routine, and even your water chemistry. These are the factors that separated the winners from the also-rans in this comparison.Inline or Offline: Match the Feeder to Your Plumbing
This is the single biggest decision, and it’s the one buyers most often get wrong. Inline chlorinators like the Hayward CL2002S and Rainbow 320 are spliced directly into your return line, which looks cleaner and tends to be more reliable long-term, but they require cutting pipe — realistic for new installations or major renovations, awkward otherwise. Offline feeders like the CL220EF and XtremepowerUS offline model connect via smaller bypass hoses with a drilling template, so they retrofit onto an existing system in an afternoon. A common mistake is buying an inline unit for an already-finished setup and discovering the installation cost exceeds the feeder itself. If you’re not replumbing anything, offline is almost always the smarter path.
Tablet Capacity Versus Refill Frequency
Capacity ranges from roughly 4 pounds to 9-plus pounds across this category, and the difference is bigger than it sounds. A small feeder on a large pool forces weekly refills, and every lid opening is a chance for a worn O-ring to start leaking or for chlorine gas to escape while you work. In this comparison, 9-pound units consistently won for pools above 20,000 gallons because three-plus weeks between refills changes the maintenance rhythm entirely. That said, oversized feeders on small above-ground pools waste money and can trap tablets that dissolve unevenly. Match capacity to pool volume rather than defaulting to the biggest option.
Output Control Precision Matters More Than You’d Expect
Every feeder here has a dial or valve, but they are not equally precise. Cheap control valves often have a meaningful difference between “off” and the lowest setting, which is a real problem for small pools and spas where a trickle of tablets overshoots sanitizer levels quickly. Hayward and Pentair valves held consistent low-flow settings during normal operation patterns, which is one reason they rank higher. If your pool is under 15,000 gallons or you run a spa on the same loop, treat fine-grained output control as a must-have, not a nice-to-have. For large pools with heavy bather loads, almost any dial will spend its life mid-range anyway, so precision matters less.
Build Quality and Parts Availability
A chlorinator lives in a harsh environment: concentrated chlorine, UV exposure, freeze-thaw cycles, and constant pressure. The failure points are predictable — lid O-rings, control valves, and the check valve that prevents back-siphoning. What separates premium brands is that replacement parts stay available for a decade or more, turning a $15 seal swap into a fix instead of a full replacement. Third-party clones often cost half as much upfront but can become disposable when a proprietary lid or valve fails. Check the parts situation for the exact model before buying, especially for compatible units like the R171016 and R171096, where some components interchange with the originals and some don’t.
Chlorine Only, or Chlorine and Bromine
Several feeders in this lineup, including the Rainbow 320, are rated for both chlorine and bromine tablets, while others are chlorine-only. This sounds trivial until you switch sanitizer systems — many spa owners move to bromine, and putting bromine tablets in a chlorine-only feeder accelerates wear on seals and internals. If there’s any chance you’ll change sanitizers or run a spa off the same equipment, the dual-rated models give you flexibility for the same money. Also confirm your feeder accepts standard 3-inch tablets; a few compact units require smaller tablets or sticks, which cost more per pound of chlorine.
Above-Ground Versus In-Ground Compatibility
Not every feeder works with every pool type, and product listings don’t always make this clear. Above-ground pools typically have flexible hose plumbing and lower flow rates, which suits feeders designed with hose-barb or smaller fittings; in-ground pools with rigid PVC need standard threaded or slip connections. Universal models like the XtremepowerUS inline unit and Hayward’s dual-rated feeders handle both, which is why they rank well for mixed-use households and buyers who aren’t sure of their fitting sizes. When in doubt, photograph your equipment pad and return line before ordering — thread size mismatches are the most common return reason in this category.
Frequently Asked Questions
Can I install an inline chlorinator on an existing pool without replumbing?
You can, but it requires cutting into your return line, draining consideration, and confident PVC work — for most existing setups, an offline feeder is the better route. Offline units like the Hayward CL220EF tap into the line through small hoses using a drill template, so the main plumbing stays intact. If your equipment pad is cramped or your pipes are rigid and awkwardly routed, retrofitting inline becomes a genuine plumbing project rather than a weekend task. The exception is if you’re already replacing your filter or pump, when adding an inline unit costs almost no extra labor. Buyers who plan ahead during a renovation almost always end up happier with an inline installation.
Are third-party chlorinators compatible with Hayward and Pentair systems as good as the originals?
Compatible units from brands like XtremepowerUS and MAYGO generally perform the same basic function reliably, and several — such as the R171096 and R171016 — are designed as direct swaps for specific Rainbow models with matching threads and fittings. Where they typically fall short is materials consistency and parts support: O-rings and lids may wear faster, and finding exact replacements years later can be hit-or-miss. If you’re comfortable swapping a seal occasionally and want to spend less upfront, the compatibles are a legitimate choice. If you want a feeder you install once and forget for five years, the name-brand units earn their premium.
How do I know what tablet capacity I actually need?
A practical rule is that a 9-pound feeder suits pools of roughly 20,000 gallons and up, while smaller pools and most above-ground setups do fine with 4 to 6 pounds of capacity. The real question is refill tolerance: a feeder that’s too small means weekly lid openings, and every opening wears the O-ring and exposes you to concentrated chlorine fumes. One factor many buyers overlook is that partially used tablets continue dissolving while the feeder sits, so oversized units can waste tablets at season’s end. If you close your pool each winter, a right-sized feeder wastes less chemistry than an oversized one come fall.
Should the chlorinator go before or after the heater and other equipment?
Always after. A chlorinator must sit downstream of the heater, filter, and any automation, because concentrated chlorinated water flowing into equipment degrades heat exchangers and seals prematurely. Most manufacturers specify the feeder as the last component before water returns to the pool, and some warranties are voided if you plumb it otherwise. If you’re installing offline, placement still matters — the feeder’s inlet hose should draw from after the heater. This is also why a working check valve matters: it stops concentrated chlorine from back-siphoning into equipment when the pump shuts off.
Can I use the same feeder for chlorine and bromine tablets?
Only if the feeder is explicitly rated for both — models like the Pentair Rainbow 320 are, while many budget units are chlorine-only. Bromine chemistry is more aggressive toward certain plastics and seals, so using it in a chlorine-only feeder shortens the unit’s life and can cause premature cracking or leaks. This matters most for spa owners, since bromine is the more common sanitizer choice in hot water. Even in dual-rated feeders, never mix leftover chlorine and bromine tablets in the same chamber; the reaction is violent. If you might switch sanitizers down the road, buying a dual-rated model now costs little and saves a full replacement later.
Conclusion
After comparing all 15 feeders, the right choice comes down to your plumbing, your pool size, and how much you value long-term parts support. Best overall goes to the Hayward CL2002S — it balances capacity, build quality, and output control better than anything else in the lineup, and Hayward’s parts availability makes it a decade-long investment. For best value, the XtremepowerUS Inline Automatic Chlorinator and Hydrotools by Swimline 8750 match the big brands on capacity and core function at a meaningfully lower cost, which suits budget-conscious owners of average-sized pools.
For the premium buyer with a large in-ground pool or a spa on the same loop, the Pentair Rainbow 320 justifies its price with dual chlorine/bromine support and exceptional durability. Beginners and owners of existing setups should start with an offline feeder — the Hayward CL220EF for in-ground pools or the XtremepowerUS offline model for above-ground — because retrofitting without cutting pipe removes the scariest part of the job. And if you’re replacing a failed unit, match your existing plumbing first: the R171096 and R171016 are direct swaps for Rainbow 320 and 300 installations respectively, making them the path of least resistance. Whatever you choose, size the capacity to your pool, plumb the feeder last in line, and buy for the parts availability you’ll want three summers from now.
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