Automatic pool chlorinators feed chlorine or bromine tablets into pool water, reducing the need to add sanitizer by hand. I rank the Hayward CL200EF as the best overall pick for in-ground pool owners seeking a dedicated in-line feeder, while the Pentair Rainbow 320 stands out for buyers who want a recognized in-line option, and the Hayward CL220EF suits installations that call for an off-line design. The key tradeoff is between in-line plumbing integration and off-line installation flexibility, alongside capacity, fit, and service access. Compatibility matters: an otherwise suitable feeder can mean extra fittings or plumbing work if it does not match your setup. Read on for the full comparison and guidance on choosing the right automatic pool chlorinator for your pool.
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Key Takeaways
- In-line and off-line designs serve different installations: the CL200EF and Rainbow 320 connect to the pool plumbing, while the CL220EF and XtremepowerUS 9 lb off-line feeder offer an alternative layout.
- The Hayward CL200EF leads this lineup for a dedicated in-ground in-line use case; the Rainbow 320 is a strong alternative when a Pentair-compatible feeder is the better fit.
- Capacity alone does not determine convenience: the 9 lb CL220EF and U.S. Pool Supply feeder may reduce refill frequency, but installation fit and access still matter.
- Compatibility claims need close checking: the two R171096 listings are associated with Rainbow 320 compatibility, but buyers should verify included connections and dimensions before ordering.
- This roundup includes several similar feeder formats rather than one universal solution: choose among in-line, off-line, and replacement-style options based on plumbing layout, pool type, and maintenance preferences.
| Hayward CL220EF Off-Line Chemical Feeder, 9 lb Capacity |  | Best Off-Line Pick for Fume Containment | Brand: Hayward | Model: CL220EF | Feeder type: Off-line automatic chemical feeder | VIEW LATEST PRICE | See Our Full Breakdown |
| Pentair Rainbow 300 Automatic Pool and Spa Feeder |  | Best Enclosed Feeder for Pools and Spas | Series: 300 | Design: Completely enclosed | Venting: No special venting required | VIEW LATEST PRICE | See Our Full Breakdown |
| XtremepowerUS Inline Automatic Pool Chlorinator, 3-Inch Tablets |  | Best for Small Pools Needing Adjustable In-Line Feeding | Installation: In-line, in pool water return line | Compatible with: Hayward CL200 | Tablet size: 3 inches | VIEW LATEST PRICE | See Our Full Breakdown |
| Hayward CL200EF Automatic Chlorine Feeder for In-Ground Pools |  | Best Off-Line Pick for Output Adjustment | Brand: Hayward | Model: CL200EF | Capacity: Up to 9 lb | VIEW LATEST PRICE | See Our Full Breakdown |
| Pentair Rainbow 320 Automatic In-Line Chlorine/Bromine Feeder |  | Best High-Capacity In-Line Feeder for Pools and Spas | Brand: Pentair | Model: R171096 | Compatible settings: Pools and spas | VIEW LATEST PRICE | See Our Full Breakdown |
| XtremepowerUS Off-Line Automatic Pool Chlorinator Feeder, 9 lb Capacity |  | Best Off-Line Option for Smaller Pools | Installation type: Off-line | Tablet compatibility: 3-inch slow-dissolving chlorine or bromine tablets | Capacity: 9 lb | VIEW LATEST PRICE | See Our Full Breakdown |
| R171096 Automatic In-Line Pool Chlorinator, Compatible with Pentair Rainbow 320 |  | Best Replacement for Rainbow 320 Setups | Model: R171096 | Compatibility: Pentair R171096 and Rainbow 320 | Material: ABS plastic | VIEW LATEST PRICE | See Our Full Breakdown |
| R171096 Automatic In-Line Chlorine and Bromine Feeder with Tube and Bushing |  | Best for a Simple Rainbow 320-Compatible Replacement | Brand: Sejaede | Model: R171096 | Compatibility: Rainbow 320 | VIEW LATEST PRICE | See Our Full Breakdown |
| U.S. Pool Supply Professional In-Line Automatic Chlorine Feeder, 9 lb |  | Best for Easy Chemical-Level Checks | Model: USP CF-478 | Chemical capacity: 9 lb (4 kg) | Compatible chemicals: Slow-dissolving trichlor or bromine tablets and sticks | VIEW LATEST PRICE | See Our Full Breakdown |
| Hayward CL100 Automatic Chlorine Feeder |  | Best Compact Feeder for 3-Inch Tablets | Model: CL100 | Tablet diameter: 3 inches | Flow rate: 50 gpm | VIEW LATEST PRICE | See Our Full Breakdown |
| Swimline Hydrotools 8750 In-Line Automatic Chlorine Feeder |  | Best for Adjustable, High-Capacity Feeding | Brand: Swimline Hydrotools | Model: 8750 | Type: In-line automatic chlorine feeder | VIEW LATEST PRICE | See Our Full Breakdown |
| Hayward CL200 In-Line Automatic Chemical Feeder for Pools |  | Best for Chlorine-or-Bromine Flexibility | Brand: Hayward | Model: CL200 | Type: In-line automatic chemical feeder | VIEW LATEST PRICE | See Our Full Breakdown |
| automatic pool chlorinator | Model | Brand | Material |
|---|---|---|---|
| Hayward CL220EF Off-Line Chemi | CL220EF | Hayward | — |
| Pentair Rainbow 300 Automatic | — | — | — |
| XtremepowerUS Inline Automatic | — | — | Heavy-duty resin |
| Hayward CL200EF Automatic Chlo | CL200EF | Hayward | — |
| Pentair Rainbow 320 Automatic | R171096 | Pentair | — |
| XtremepowerUS Off-Line Automat | — | — | Heavy-duty resin |
| R171096 Automatic In-Line Pool | R171096 | — | ABS plastic |
| R171096 Automatic In-Line Chlo | R171096 | Sejaede | — |
| U.S. Pool Supply Professional | USP CF-478 | — | ABS plastic |
| Hayward CL100 Automatic Chlori | CL100 | — | Plastic |
| Swimline Hydrotools 8750 In-Li | 8750 | Swimline Hydrotools | Reinforced thermoplastic |
| Hayward CL200 In-Line Automati | CL200 | Hayward | — |
More Details on Our Top Picks
Hayward CL220EF Off-Line Chemical Feeder, 9 lb Capacity
The Hayward CL220EF suits pool owners who want an off-line feeder with an enclosed body and straightforward access for refilling. Its 9-pound capacity means fewer tablet reloads than a smaller feeder, while the Easy Lok threaded cover provides access without special venting. Compared with the Hayward CL200EF, this model’s supplied details highlight its ABS body, Viton seal, and enclosed design rather than an adjustable sanitizer-output dial. That makes containment and service access its clearest strengths, but gives buyers less documented control detail than the CL200EF offers. The off-line layout also means it is not a direct fit for someone specifically seeking an in-line unit. Tablets or sticks are not included, so plan to source compatible sanitizer separately.
Pros:- Enclosed ABS body helps contain chemical fumes.
- 9-pound capacity reduces how often tablets or sticks need replenishing.
- Easy Lok threaded cover allows convenient access.
- Designed to fit most PVC pool plumbing and requires no special venting.
Cons:- Off-line installation is not suited to buyers seeking an in-line return-line feeder.
- Tablets or sticks are not included.
- The supplied specifications do not list an adjustable feed-rate control.
Best for: Pool owners with compatible PVC plumbing who want an enclosed off-line feeder with a 9-pound capacity and easy cover access.
Not ideal for: Owners who need an in-line feeder or want a model whose supplied specifications clearly include an adjustable output dial.
- Brand:Hayward
- Model:CL220EF
- Feeder type:Off-line automatic chemical feeder
- Capacity:9 lbs
- Body material:ABS
- Cover:Easy Lok threaded cover
- Seal material:Viton
- Item weight:4 lbs
Our verdict“Choose the CL220EF if an enclosed, easy-access off-line feeder matters more than an in-line layout or documented output adjustment.”
Pentair Rainbow 300 Automatic Pool and Spa Feeder
The Pentair Rainbow 300 is a fit for buyers who prioritize an enclosed feeder for either a pool or spa and want a design that does not call for special venting. Its completely enclosed construction is the headline distinction: compared with the Hayward CL220EF, the available product details do not specify a 9-pound capacity, ABS body, or Easy Lok cover, so buyers get less information about loading and service access. The Rainbow 300’s stated advantage is its enclosed design and NSF listing, not a documented tablet capacity or adjustment range. That makes it harder to judge refill frequency and feed control from the supplied specifications. Unions are not included, which may add a separate plumbing-parts task. Choose it for its pool-and-spa scope and enclosure, not for capacity details that are not provided.
Pros:- Completely enclosed feeder design.
- Requires no special venting.
- Designed for both pools and spas.
- NSF Listed.
Cons:- Unions are not included.
- The supplied product details do not state tablet capacity.
- The supplied specifications do not describe an adjustable feed-rate control.
Best for: Pool and spa owners who want a completely enclosed automatic feeder and value an NSF-listed design.
Not ideal for: Buyers who need a stated tablet capacity, documented feed-rate adjustment, or included unions before choosing a feeder.
- Series:300
- Design:Completely enclosed
- Venting:No special venting required
- Compatible settings:Pools and spas
- Listing:NSF Listed
- Unions:Not included
Our verdict“Pick the Rainbow 300 if an enclosed, NSF-listed pool-and-spa feeder is your priority and you can verify capacity and plumbing needs before purchase.”
XtremepowerUS Inline Automatic Pool Chlorinator, 3-Inch Tablets
For an owner who wants chlorine or bromine fed through the return line, the XtremepowerUS in-line chlorinator combines a 9-pound tank with an adjustable dial to regulate delivery. That dial gives it a practical control advantage over the Pentair Rainbow 300, whose supplied details do not specify an adjustment control. It is made for above-ground and small in-ground pools, so its stated fit is narrower than the Pentair Rainbow 320, which is described for pools and spas. The tradeoff is installation: this unit must connect to the return line after the filter and heater, so it is not a simple substitute for an off-line feeder such as the Hayward CL220EF. It accepts 3-inch tablets, but tablets are sold separately; check plumbing compatibility and available installation space before choosing it.
Pros:- Adjustable dial helps regulate chlorine or bromine feed.
- 9-pound tank provides substantial tablet capacity.
- Accepts 3-inch slow-dissolving tablets.
- Specified for above-ground and small in-ground pools.
Cons:- Requires installation in the return line after the filter and heater.
- Tablets are sold separately.
- Its stated pool fit is narrower than the Pentair Rainbow 320’s pool-and-spa scope.
Best for: Owners of above-ground or small in-ground pools who want an in-line feeder with adjustable output and use 3-inch tablets.
Not ideal for: Pool owners who cannot modify the return line, need an off-line feeder, or use tablet sizes other than 3 inches.
- Installation:In-line, in pool water return line
- Compatible with:Hayward CL200
- Tablet size:3 inches
- Tank capacity:9 lbs
- Control:Adjustable dial valve
- Maximum pressure:50 PSI
- Material:Heavy-duty resin
- Use:Above-ground and small in-ground pools
Our verdict“Choose this XtremepowerUS model if your small pool has compatible return-line plumbing and you want adjustable feeding from 3-inch tablets.”
Hayward CL200EF Automatic Chlorine Feeder for In-Ground Pools
The Hayward CL200EF gives in-ground pool owners a clear reason to choose it over the CL220EF: its adjustable sanitizer-output dial is specified for regulating delivery. Both Hayward feeders use an off-line configuration and hold up to 9 pounds, but the CL220EF’s supplied details put more emphasis on its enclosed ABS body, Viton seal, and Easy Lok cover. The CL200EF instead makes feed adjustment its defining feature, which can help owners tune output to their pool’s sanitation needs. The off-line plumbing layout remains a real constraint; buyers seeking a return-line installation should look at the Pentair Rainbow 320 or XtremepowerUS in-line model instead. Chlorine tablets are required and are not stated to be included, so this is an automated delivery system, not a complete sanitizer supply.
Pros:- Adjustable dial lets owners regulate sanitizer output.
- Holds up to 9 pounds of chlorine tablets.
- Automates chlorine distribution for routine pool maintenance.
- Designed for in-ground swimming pools.
Cons:- Requires an off-line plumbing configuration.
- Chlorine tablets are not stated to be included.
- The supplied details do not specify body or seal materials.
Best for: In-ground pool owners with off-line plumbing who want a 9-pound feeder and a dial for adjusting sanitizer output.
Not ideal for: Owners who need an in-line return-line model, or buyers who prioritize the CL220EF’s specified ABS body and Easy Lok cover.
- Brand:Hayward
- Model:CL200EF
- Capacity:Up to 9 lb
- Installation:Offline plumbing configuration
- Control:Adjustable sanitizer output dial
- Intended use:In-ground swimming pools
Our verdict“Choose the CL200EF when adjustable output is the deciding feature and your in-ground pool is set up for off-line plumbing.”
Pentair Rainbow 320 Automatic In-Line Chlorine/Bromine Feeder
The Pentair Rainbow 320 is the strongest fit here for buyers who want an in-line feeder with clearly stated tablet capacity and pool-and-spa compatibility. It holds 11 large or 98 small tablets, giving shoppers more capacity detail than the Rainbow 300 and more stated room for large tablets than the 9-pound XtremepowerUS model. Its included 2-inch slip PVC fitting and adapters for 1½-inch connections can simplify matching common return-line sizes, though unions are not included. Unlike the off-line Hayward CL200EF, this feeder installs in the return line, so buyers need a suitable plumbing layout. It accepts bromine or slow-dissolving trichlor tablets, not an unrestricted range of chemicals. With no special venting required and a one-year warranty, it is a practical capacity-led choice, but not the pick for off-line installation.
Pros:- Holds 11 large or 98 small tablets.
- Works with pools and spas.
- Includes a 2-inch slip PVC fitting with adapters for 1½-inch connections.
- Requires no special venting.
Cons:- Unions are not included.
- Limited to bromine or slow-dissolving trichlor tablets.
- Requires installation in the return line.
Best for: Pool or spa owners seeking a high-capacity in-line feeder with adapters for 1½-inch connections and support for bromine or slow-dissolving trichlor.
Not ideal for: Owners who need an off-line feeder, require included unions, or use tablets outside the specified bromine and slow-dissolving trichlor types.
- Brand:Pentair
- Model:R171096
- Compatible settings:Pools and spas
- Tablet capacity:11 large or 98 small tablets
- Compatible tablets:Bromine or slow-dissolving trichlor
- Fitting:2-inch slip PVC with adapters for 1½-inch connections
- Installation:In return line; no special venting required
- Item weight:4.5 pounds
- Warranty:1 year
Our verdict“Choose the Rainbow 320 for a high-capacity in-line setup serving a pool or spa, provided its tablet types and plumbing connections match your system.”
XtremepowerUS Off-Line Automatic Pool Chlorinator Feeder, 9 lb Capacity
The XtremepowerUS is a practical choice for owners of above-ground pools or small in-ground pools who want a feeder that does not sit directly in the main return line. Its off-line installation can reduce added resistance in the pool plumbing, while the 9 lb tank means fewer tablet refills than a compact feeder. A dial lets you adjust the feed rate, and the tank accepts slow-dissolving chlorine or bromine tablets up to 3 inches wide. Compared with the U.S. Pool Supply Professional In-Line Feeder, this model trades a simpler plumbing fit for off-line installation; it is not the better match for every setup. Its stated pool scope is limited, tablets are separate, and the product data does not specify installation fittings. I would choose it for capacity and flow considerations, not for large-pool versatility.
Pros:- Off-line installation avoids placing the feeder directly in the main return line
- 9 lb capacity reduces how often tablets need replenishing
- Dial control allows feed-rate adjustment
- Accepts slow-dissolving chlorine or bromine tablets up to 3 inches
Cons:- Intended for above-ground pools and small in-ground pools rather than larger systems
- Tablets must be purchased separately
- Installation fittings are not specified in the product data
Best for: Above-ground pool owners and people with small in-ground pools who want a 9 lb off-line feeder with adjustable dosing.
Not ideal for: Owners of large in-ground pools or anyone seeking a clearly specified, fittings-included installation kit.
- Installation type:Off-line
- Tablet compatibility:3-inch slow-dissolving chlorine or bromine tablets
- Capacity:9 lb
- Feed control:Dial knob
- Maximum pressure:50 PSI
- Material:Heavy-duty resin
- Pool compatibility:Above-ground pools and small in-ground pools
- Model number:90156
Our verdict“Choose this feeder if you have a smaller pool and prefer an off-line design with a generous tablet reserve.”
R171096 Automatic In-Line Pool Chlorinator, Compatible with Pentair Rainbow 320
This R171096 feeder is aimed at buyers replacing a Pentair R171096 or Rainbow 320, rather than owners choosing a chlorinator without plumbing constraints. Its capacity—up to 11 large or 98 small tablets—and adjustable flow control support a broad stated range of pool and spa sizes, from 6,500 to 70,000 gallons. The enclosed ABS body helps keep tablets contained, and included adapters cover 2-inch PVC slip fittings and 1.5-inch connections. Compared with the Sejaede R171096 feeder, this listing spells out capacity, fittings, and a 12-month warranty, making replacement planning clearer. The tradeoff is the in-line installation: plumbing must match, and this is not a universal drop-in choice for every return line. I would favor it when compatibility is the main concern, not when an off-line layout is preferred.
Pros:- Designed to replace Pentair R171096 and Rainbow 320 feeders
- Holds up to 11 large or 98 small tablets
- Adjustable flow control supports dosing changes
- Includes 2-inch slip fittings, 1.5-inch adapters, and a drain plug
Cons:- Requires a compatible pool plumbing setup
- In-line installation may not suit owners seeking an off-line arrangement
Best for: Pool and spa owners replacing a Pentair R171096 or Rainbow 320 who need specified adapters and a substantial tablet capacity.
Not ideal for: Buyers with different plumbing or those who want an off-line feeder that does not depend on return-line compatibility.
- Model:R171096
- Compatibility:Pentair R171096 and Rainbow 320
- Material:ABS plastic
- Tablet capacity:11 large or 98 small tablets
- Pool size range:6,500–70,000 gallons
- Flow control:Adjustable
- Installation fittings:2-inch PVC slip fittings and 1.5-inch adapters
- Warranty:12 months
Our verdict“Pick this replacement when your plumbing matches the Rainbow 320 format and you want capacity and installation details stated upfront.”
R171096 Automatic In-Line Chlorine and Bromine Feeder with Tube and Bushing
The Sejaede R171096 is a more lightly specified alternative for buyers who need a Rainbow 320-compatible in-line feeder and value the included tube and bushing. Adjustable feed control and support for chlorine or bromine tablets give it flexible chemical use for pools and spas. Its stated corrosion-resistant construction is another useful point for equipment exposed to treated water. Compared with the other R171096 replacement feeder in this lineup, however, this product provides no listed tablet capacity, pool-size range, fitting dimensions, or warranty. That makes it harder to verify whether it will match a particular system or reduce refill frequency. I would treat it as a fit-specific replacement candidate and confirm plumbing details before choosing it; buyers who want more documented specifications have a clearer path with the other R171096 option.
Pros:- Designed for compatibility with the Rainbow 320
- Adjustable feed control allows dosing changes
- Works with chlorine or bromine tablets
- Includes a chlorinator tube and bushing
Cons:- Tablet capacity is not specified
- Fitting dimensions and pool-size range are not provided
- Warranty information is not listed
Best for: Rainbow 320 owners seeking a chlorine- or bromine-compatible replacement that includes a tube and bushing, after confirming fit.
Not ideal for: Buyers who need a stated tablet capacity, pool-size range, warranty, or detailed plumbing dimensions before purchase.
- Brand:Sejaede
- Model:R171096
- Compatibility:Rainbow 320
- Use:Pools and spas
- Installation:In-line, return line
- Included components:Chlorinator tube and bushing
- Tablet type:Chlorine or bromine
- Construction:Corrosion-resistant
Our verdict“Consider this as a Rainbow 320-compatible replacement only after confirming its dimensions and capacity meet your system’s needs.”
U.S. Pool Supply Professional In-Line Automatic Chlorine Feeder, 9 lb
The U.S. Pool Supply feeder suits owners who want to see when the chemical supply is running low without opening the unit: its transparent easy-lock cover makes the remaining tablets visible. It holds up to 9 lb of slow-dissolving trichlor or bromine tablets and sticks, and the adjustable dial provides control over the feed rate. Installation accessories and a lid wrench are included, a more complete package than the XtremepowerUS off-line feeder’s listed contents. The key limitation is fit: compatibility is specified for the Hayward CL200, so buyers should check their plumbing before treating it as a general-purpose in-line choice. Tablets and sticks are not included, and the product data does not give a pool-size range. I would choose it for visibility and refill convenience when the stated compatibility matches, not for uncertain plumbing setups.
Pros:- Transparent cover makes it easier to check the remaining chemical supply
- 9 lb capacity accepts slow-dissolving trichlor or bromine tablets and sticks
- Adjustable dial controls feed rate
- Includes installation accessories, instructions, and a lid wrench
Cons:- Tablets and sticks are sold separately
- Compatibility is specified for Hayward CL200 chlorinators
- A pool-size range is not provided
Best for: Hayward CL200 owners who want a 9 lb in-line feeder with a visible chemical level and included installation accessories.
Not ideal for: Pool owners with plumbing that is not compatible with the Hayward CL200, or buyers who need a specified pool-size range.
- Model:USP CF-478
- Chemical capacity:9 lb (4 kg)
- Compatible chemicals:Slow-dissolving trichlor or bromine tablets and sticks
- Material:ABS plastic
- Feed control:Adjustable dial control valve
- Cover:Transparent easy-lock cover with O-ring seal
- Compatibility:Hayward CL200 chlorinator
- Included accessories:Installation accessories, instruction guide, and lid wrench
Our verdict“Choose this feeder if you have a compatible Hayward CL200 setup and want to check tablet levels without opening the lid.”
Hayward CL100 Automatic Chlorine Feeder
The Hayward CL100 is the straightforward pick for owners who want an automatic feeder tied to their pump and filter system, without needing the larger stated capacities of the 9 lb XtremepowerUS or U.S. Pool Supply models. Its adjustable feed-rate dial lets owners change chlorine delivery, while the threaded cover provides access for loading 3-inch tricolor tablets. The product data lists a 50 gpm flow rate and a compact 16-by-8-by-8-inch body, which can help buyers judge whether it suits their equipment area. Compared with the XtremepowerUS off-line feeder, this is a pump-system-dependent option rather than an off-line design, and its tablet compatibility is narrower. It is not a fit for smaller tablet formats or systems without a compatible pump and filter setup. I would choose it for a simple, specified tablet format—not for broad chemical flexibility.
Pros:- Adjustable feed-rate dial supports dosing changes
- Threaded cover allows access for loading tablets
- Designed to work with pool or spa pump and filter systems
- Listed dimensions help buyers check equipment-area fit
Cons:- Requires 3-inch tablets
- Installation and operation depend on a compatible pump and filter system
- Product data does not state a tablet capacity
Best for: Pool or spa owners with a compatible pump and filter system who use 3-inch tricolor tablets and want adjustable chlorine feeding.
Not ideal for: Buyers who use tablets of another size, need a stated high-capacity tank, or cannot connect a feeder to a compatible pump and filter system.
- Model:CL100
- Tablet diameter:3 inches
- Flow rate:50 gpm
- Material:Plastic
- Color:Black
- Dimensions:16 x 8 x 8 inches
- Power source:AC, AC/DC
- System compatibility:Pool or spa pump and filter system
Our verdict“Choose the CL100 if your pool system supports it and you want an adjustable feeder dedicated to 3-inch tricolor tablets.”
Swimline Hydrotools 8750 In-Line Automatic Chlorine Feeder
The Swimline Hydrotools 8750 suits pool owners who want a sizable tablet supply connected directly to their existing plumbing. Its 9-pound capacity can reduce how often you need to replenish tablets, while adjustable output lets you tune chlorine delivery to pool conditions. Unlike the Hayward CL200, which is also an in-line option but lists compatibility with chlorine and bromine tablets, the 8750’s supplied details focus on chlorine and specify compatibility with both above-ground and in-ground pools. The reinforced thermoplastic body is designed to resist UV exposure and corrosion, a useful fit for equipment exposed to poolside conditions. The tradeoff is installation: this feeder must connect to pool plumbing and rely on the circulation system. Product details also conflict over whether it is an in-line feeder or a floating dispenser, so confirm the configuration before buying.
Pros:- 9-pound capacity can mean fewer tablet refills
- Adjustable output gives owners control over chlorine delivery
- Designed for above-ground and in-ground pools
- Reinforced thermoplastic is designed to resist UV exposure and corrosion
Cons:- Requires a connection to pool plumbing and the existing circulation system
- Product information conflicts on whether the unit is in-line or floating
- Supplied details specify chlorine use, unlike the Hayward CL200’s stated chlorine-or-bromine compatibility
Best for: Above-ground or in-ground pool owners with plumbing access who want adjustable chlorine delivery and a 9-pound feeder capacity.
Not ideal for: Pool owners seeking a floating, no-plumbing dispenser or anyone who needs unambiguous confirmation of the unit’s installation style before purchase.
- Brand:Swimline Hydrotools
- Model:8750
- Type:In-line automatic chlorine feeder
- Capacity:9.0 lbs
- Output:Adjustable
- Pool compatibility:Above-ground and in-ground pools
- Material:Reinforced thermoplastic
Our verdict“Choose the Hydrotools 8750 if you want a high-capacity, adjustable feeder for plumbed pools and can verify its configuration before ordering.”
Hayward CL200 In-Line Automatic Chemical Feeder for Pools
The Hayward CL200 is a practical choice for pool or spa owners who want to use either slow-dissolving trichlor or bromine tablets in an in-line feeder. Its adjustable feed-rate control gives you a way to tune dispensing, while the threaded cover provides access when tablets need replenishing. Compared with the Swimline Hydrotools 8750, the CL200 stands out for its stated bromine compatibility and clearly described in-line design; the Hydrotools listing instead gives a 9-pound capacity and covers both above-ground and in-ground pools. The CL200’s corrosion-resistant ABS body and Viton seal are practical material choices, but its supplied specifications do not state capacity or pool-type compatibility. It also depends on a pump and filter system, so it is not a fit for buyers seeking a standalone or floating dispenser.
Pros:- Accepts large or small slow-dissolving trichlor or bromine tablets
- Adjustable feed-rate control supports changes to tablet dispensing
- Threaded cover provides access for refilling
- Corrosion-resistant ABS body and Viton seal
Cons:- Requires a pump and filter system
- Supplied product data does not state tablet capacity
- Supplied product data does not specify above-ground or in-ground pool compatibility
Best for: Pool and spa owners with a pump-and-filter setup who want the option to feed slow-dissolving chlorine or bromine tablets.
Not ideal for: Buyers who need a stated feeder capacity or confirmed above-ground and in-ground pool compatibility, or who cannot connect a feeder to their circulation system.
- Brand:Hayward
- Model:CL200
- Type:In-line automatic chemical feeder
- Tablet compatibility:Large or small, slow-dissolving trichlor or bromine tablets
- Body material:ABS
- Seal material:Viton
- Feed rate:Adjustable
- Item weight:4 ounces
Our verdict“Choose the CL200 if tablet-type flexibility matters more to you than a published capacity or specified pool-type fit.”
How We Picked
I compared these automatic pool chlorinators on the factors that change the buying decision: in-line versus off-line installation, stated capacity, intended pool use, compatibility information, and the practical effort involved in fitting and refilling each feeder. I gave more weight to clear use cases and established fit details than to broad claims that a feeder suits every pool. I also considered whether the listed design gives buyers a sensible path when they need a replacement or a different plumbing arrangement.
The ranking reflects fit and decision clarity, not a claim that every model performs identically or suits every pool. The Hayward CL200EF ranks first for its straightforward in-ground in-line role; the Rainbow 320 follows as a recognizable alternative in the same general format. Off-line units rank well for installations where cutting into the return line is undesirable, while compatibility-focused and less-detailed listings sit lower because buyers may need to confirm more specifics before purchase. I do not treat listed capacity or brand familiarity as a substitute for checking pool plumbing, tablet type, and installation instructions.
| automatic pool chlorinator | Brand | Material |
|---|---|---|
| Hayward CL220EF Off-Line Chemi | Hayward | — |
| Pentair Rainbow 300 Automatic | — | — |
| XtremepowerUS Inline Automatic | — | Heavy-duty resin |
| Hayward CL200EF Automatic Chlo | Hayward | — |
| Pentair Rainbow 320 Automatic | Pentair | — |
| XtremepowerUS Off-Line Automat | — | Heavy-duty resin |
| R171096 Automatic In-Line Pool | — | ABS plastic |
| R171096 Automatic In-Line Chlo | Sejaede | — |
| U.S. Pool Supply Professional | — | ABS plastic |
| Hayward CL100 Automatic Chlori | — | Plastic |
| Swimline Hydrotools 8750 In-Li | Swimline Hydrotools | Reinforced thermoplastic |
| Hayward CL200 In-Line Automati | Hayward | — |
Factors to Consider When Choosing Automatic Pool Chlorinators
Choosing a feeder is as much a plumbing and maintenance decision as a capacity decision. I would start by checking how the unit will connect to the pool system, then work through tablet compatibility, access, and the amount of adjustment you want to manage.
Match the feeder layout to your plumbing
An in-line feeder becomes part of the return plumbing, so it suits owners planning a permanent installation and comfortable with the required plumbing work. An off-line model draws water through separate connections and can suit layouts where placing the feeder directly in the return line is impractical. Do not choose based on the label alone: inspect the available pipe space, flow direction, and manufacturer installation requirements. A poor location can complicate servicing or expose equipment to concentrated chemical water. If you are unsure about cutting or modifying pool plumbing, ask a pool professional to assess the setup before buying.
Check tablet type and feeder instructions
Feeders are designed for particular sanitizer formats, and some models are listed for chlorine and bromine while others are presented as chlorine feeders. Never assume the chemicals can be mixed or that a feeder intended for one tablet type can safely handle another. Follow the unit manual and chemical label, including guidance for changing sanitizer types. Residue from a previous chemical can create a dangerous reaction if products are combined. Confirm the approved tablet type before purchase, especially when replacing an existing feeder or changing your pool-care routine.
Choose capacity around pool use, not the biggest number
A larger stated capacity can mean fewer refill trips, but it does not automatically mean better sanitation or less oversight. Tablet use changes with pool volume, swimmer load, weather, and water conditions, so the same feeder setting will not suit every pool. Think about how often you can inspect and refill the unit, then compare that routine with the feeder’s capacity and adjustment method. Avoid packing in extra tablets or setting the feed rate high to compensate for neglected water testing. Regular testing remains necessary even when a feeder doses sanitizer automatically.
Plan for service access and safe handling
A feeder needs a place where its lid or cover can be opened safely and where routine checks are convenient. Look for clear access around the unit, and follow instructions for shutting down circulation or relieving pressure before opening it. Chlorine tablets and feeder water can be corrosive, so avoid placing the unit where leaks or spills can damage nearby equipment. Check whether seals and connections are accessible for inspection and replacement. Easy service access may matter more over time than a small difference in capacity.
Verify fittings, dimensions, and replacement status
Product names that mention compatibility do not always mean every connection, tube, or bushing is included or suited to your exact setup. Compare the feeder’s connection sizes and installation details with the existing plumbing before ordering. If replacing a unit, record its model number and inspect the parts you plan to reuse; worn fittings can cause leaks even when the new feeder itself fits. Replacement-style listings can be useful, but confirm whether the item is a complete feeder or a compatible alternative. Fit verification can prevent avoidable plumbing changes and delays.
Decide how much installation work you want to take on
The cheapest-looking or simplest-listed feeder may still require professional installation, extra fittings, or changes to the return line. An in-line model can make sense for a planned plumbing upgrade, while an off-line unit may better suit owners who want more placement flexibility. Compare the full task, including access, connections, and maintenance, rather than judging only by the product format. If you prefer not to handle pool plumbing, ask an installer which design fits your system and what additional parts are needed. Paying for a clearer fit or simpler service route can be a better choice than buying a unit that creates extra work.
Frequently Asked Questions
Should I choose an in-line or off-line automatic pool chlorinator?
Choose based on your plumbing layout and how much installation work you are prepared to take on. An in-line feeder connects to the return plumbing, which can suit a permanent installation but may require cutting or reworking pipe. An off-line feeder uses separate connections and can offer more placement flexibility, though it still needs correct routing and secure fittings. Check the manufacturer’s instructions and your equipment layout before deciding. If plumbing changes are unfamiliar, have a pool professional confirm the suitable design.
Can I use a chlorine feeder for bromine tablets?
Only use the tablet type approved in the feeder’s instructions. Some models are described as compatible with chlorine and bromine, but that does not mean every feeder supports both. Never combine different sanitizer products in one unit or add a new chemical type without following the manufacturer’s changeover instructions. Chemical residues can react dangerously, and incorrect use can damage equipment. Confirm the product manual and tablet label before loading the feeder.
Will an automatic feeder keep my pool balanced without testing?
No. A feeder meters sanitizer, but it does not measure water conditions or adjust for every change in pool use, temperature, rain, and sunlight. Continue testing sanitizer and other relevant water levels on a regular schedule, then adjust the feeder according to its instructions. If readings change unexpectedly, check the water and feeder rather than assuming the unit will correct the problem on its own. Automation reduces manual dosing; it does not replace pool maintenance.
How do I know whether a replacement feeder will fit my existing plumbing?
Start with the existing feeder’s model number, connection sizes, and installation layout, then compare those details with the new unit’s specifications. Check whether hoses, tubes, bushings, and other fittings are included or need to be purchased separately. Compatibility wording can refer to a general model family rather than every part of your installation. Inspect old connections for wear, since reusing damaged fittings can lead to leaks. When dimensions or included parts are unclear, confirm them with the manufacturer or a pool technician before ordering.
Is a larger-capacity feeder always the better choice?
Not necessarily. A larger capacity may reduce how often you refill, but the right feed rate still depends on the pool, conditions, and sanitizer demand. A unit that is awkward to access or mismatched to the plumbing can create more hassle than a smaller feeder that fits well. Consider refill frequency alongside service access, installation requirements, and how easily you can inspect the unit. Keep testing water regularly, regardless of capacity.
Conclusion
For most buyers seeking a dedicated in-ground in-line unit, I recommend the Hayward CL200EF as the best overall; choose the Hayward CL220EF as the best value-oriented off-line option when that layout better suits your plumbing and you want its stated 9 lb capacity. The Pentair Rainbow 320 is my best premium-leaning pick for buyers who prefer a Pentair-compatible in-line design, while the Hayward CL100 is a sensible beginner choice for shoppers who want a straightforward Hayward feeder option and can verify it fits their setup. For installation flexibility, compare the XtremepowerUS off-line feeder with the CL220EF; for a compatibility-focused replacement, investigate the R171096 listings and confirm exact fittings first. Match the feeder to your plumbing and approved tablet type before choosing capacity or brand.
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