Pool Chlorine Tablet Feeders: Model and Plumbing Fit Map

For R171096, confirm plumbing, chemistry and service access using the Rainbow 320 plumbing and service checklist .

Pool-chemical safety: Use only the chemistry and tablet form allowed by the exact feeder manual and chemical label. The CDC pool-chemical guidance says to keep chemicals separate, dry, and in original manufacturer-labeled containers. Never mix pool chemicals.

The Pentair Rainbow 320 R171096 is the clearest choice when you need a published tablet count, service envelope, and configuration-specific pool range. Choose a Hayward CL200-family inline feeder when its direct return-line body fits; choose the CL220-family off-line route when saddle fittings and protected tubing solve a retrofit problem. Choose a CMP Powerclean Tab Ultra only after matching its exact inline or off-line part number, pipe range, lid, and base.

That order matters more than a generic “large pool” label. Our source reconciliation found that manufacturers describe stored tablet count, maximum-rated output, plumbing configuration, and pool-volume range as different facts. Treating them as one capacity number creates a false comparison.

The handover record to request with an installation quote

A quote that names only the feeder family leaves several expensive decisions unresolved. Ask the installer to supply the exact model suffix, the matching manual revision, a marked plumbing diagram, and a photograph showing where the lid can be serviced. Record the approved chemical separately from the feeder’s capacity. A large chamber does not establish a safe operating setting.

Use this acceptance record when comparing two quotes:

Record	What a usable answer contains
Equipment identity	Exact feeder model and existing pump, filter and heater models
Installation route	Proposed connection points and required backflow protection from the applicable manuals
Service access	Actual available clearance compared with the manufacturer’s drawing
Startup responsibility	Who checks the initial water readings and explains adjustment under the sanitizer label
Routine ownership	Who tests, refills and responds when pump schedules or swimming demand change
Replacement parts	Correct seal, lid and tubing identifiers for this specific version

This is a purchasing checklist, not an installation design. An unresolved plumbing or chemical answer is a reason to obtain a qualified installer’s clarification before ordering. Extra tablet capacity can reduce handling frequency, but it cannot replace water testing or cover an unattended holiday by itself.

The model and plumbing map

Exact family	Water path	Verified decision facts	Best fit	Stop or verify before buying
Pentair Rainbow 320 R171096	Inline; bottom-feed or named top-feed setup	11 large or 98 small tablets; 17.75 × 5 × 10 inches; 19-inch lid-service envelope; 50 psi maximum; current published ranges change with feed configuration	Buyer who wants the most complete first-party capacity and service data	Confirm feed configuration, return-line layout, check-valve requirements, tablet chemistry, and installer plan
Hayward CL200 family	Inline in permanent return plumbing	Current manual publishes 2.30 lb/day at 100% and 0.63 lb/day at 50% for the CL200 pool table, plus 2.01 psi head loss at 50 gpm	Direct return line with room for the body, unions, and downstream placement	Do not use dial percentage as a linear dose; match exact suffix and union package
Hayward CL220 family	Off-line tubing with saddle fittings	Current manual covers clamps around nominal 1.5- or 2-inch pipe, two 3/8-inch saddle holes, tubing, check valve, and CL220-specific base	Retrofit where protected inlet and outlet tubing is easier than cutting in an inline body	Manual has no separate CL220 output curve; do not borrow CL200 values
CMP Powerclean Tab Ultra inline	Inline	Historical brochure includes lid variants and base/no-base parts; manual permits 1.5- or 2-inch PVC unions and asks for 6 inches of straight inlet pipe after a 90-degree elbow	Equipment pad matching the exact 25280 inline variant and service position	Manufacturer says above water level, after heater/equipment, and not in copper plumbing
CMP Powerclean Tab Ultra off-line	Off-line clamp family	Confirm the current clamp range and kit; the retained historical brochure distinguishes inline and off-line part numbers and lids	Larger-pipe retrofit where exact clamp kit and lid are known	Do not transfer inline-only capacity or installation claims to an off-line suffix

The practical rule is simple: pick the water path first, then the exact model suffix, then check service access and allowed chemistry. Compare published output or pool range only after those gates match.

What the published numbers actually mean

Pentair: configuration changes the stated range

Pentair’s current product page lists the Rainbow 320 R171096 with 11 large or 98 small slow-dissolving trichlor or bromine tablets. It gives a 6,500-27,000 gallon range in bottom-feed configuration and 18,000-70,000 gallons in the named top-feed configuration.

The maximum top-feed endpoint is about 2.6 times the bottom-feed endpoint. That does not mean a buyer can turn any 320 into a 70,000-gallon answer by moving one tube. It means configuration is part of the manufacturer’s range claim and must be confirmed in the current installation guide.

The Pentair data sheet lists 3.5 pounds across the 98-small-tablet load and 4.8 pounds across the 11-large-tablet load. The large-tablet load stores about 37% more tablet mass, but stored mass is not output. Pentair’s own 320 instructions say smaller tablets erode faster when 3-inch tablets do not provide enough residual. Tablet count, tablet mass, erosion, and achieved free chlorine are separate facts.

The 320 is the best-documented choice in this group, not a universal winner. Skip it when the return line cannot accept the exact inline layout, 19-inch lid-service envelope, required safeguards, or a safe pressure-release routine.

Hayward: CL200 and CL220 solve different plumbing jobs

Hayward’s current CL-series manual makes the split clearer than many retailer comparisons:

CL200 is inline. It is installed in the permanent return line after the heater, or after the filter when there is no heater.
CL220 is off-line. It uses small inlet and outlet tubing, saddle fittings, clamps, an inlet adapter, and a check valve around the main line.

The CL200 output table is useful but easy to misuse. For pool operation, Hayward lists 2.30 pounds per day at the 100% control position and 0.63 pound per day at 50%. The maximum entry is roughly 3.7 times the 50% entry, not twice it. The dial is therefore not a linear pounds-per-day scale, and the table is a maximum-rated result rather than a promise for a specific pool.

The same manual says its NSF qualification testing used 3-inch 99% active trichlor tablets and calls for a flow indicator upstream of a CL200. It also publishes 2.01 psi head loss at 50 gpm. Those conditions belong with the number; removing them makes the comparison look more precise than it is.

Choose the CL200 path when the direct body and union package suit the return line. Choose CL220 when two protected saddle connections and tubing offer a cleaner retrofit. Do not call CL220 “the same feeder but easier to install”: its tubing, clamps, check valve, and service points are part of the ownership job.

CMP: the part number carries the fit

CMP’s retained May 2021 brochure separates Powerclean Tab Ultra inline parts from off-line clamp parts. Within each route, the number changes again for glass, clear-plastic, or white lids and for a base. The historical brochure does not establish every current clamp-kit option; confirm the actual offered kit rather than borrowing a pipe-size range.

That makes “CMP Powerclean Ultra” an incomplete shopping identity. Copy the complete part number before ordering. The inline instruction sheet applies to the named 25280 inline variants; it supports 1.5- or 2-inch PVC unions, asks for 6 inches of straight inlet pipe after a 90-degree elbow, and says not to install in copper plumbing. It also says the feeder should sit above water level and after the heater and other equipment.

CMP permits 1- or 3-inch slow-dissolving trichlor or bromine tablets for pools in that inline manual, but it warns never to mix the two chemistries. The May 2021 brochure also gives family-level capacity claims. We have not converted those into a verified operating range for every current suffix or plumbing arrangement.

Choose in this order

Confirm the sanitation plan. A tablet feeder is not a reason to keep using stabilized tablets when the water-care plan calls for something else; the tablet feeder versus liquid-chlorine metering pump comparison covers that alternative.
Map the return line. Identify the filter, heater, valves, pipe size, copper components, water level, and usable service space.
Choose inline or off-line. Inline puts the body in the return route. Off-line adds tubing or clamps that must remain protected and inspectable; the Hayward CL2002S versus CL220 comparison sets the two connection styles side by side.
Record the complete identity. “CL200,” “CL220,” “R171096,” and CMP’s full 25280 suffixes describe materially different hardware.
Check the service envelope. The lid must open without leaning over hot, electrical, or blocked equipment. Pressure must be relieved exactly as the manual directs.
Then compare documented output. Keep every test condition, feed configuration, and limit beside the number.

This order prevents two expensive mistakes: buying a large body that cannot be serviced and choosing an off-line kit whose clamps do not fit the existing pipe.

Two inputs sit outside the model table. First, pool volume: take it from reliable construction records or measured geometry and keep units explicit, because length, width and depth in feet give cubic feet, which must then be converted to US gallons. Slopes, benches and irregular shapes need more than one guessed depth, and volume is an input to the product instructions rather than a tablets-per-week formula. Second, the quote: a cheaper installation can become inconvenient if every refill requires awkward reaching or moving unrelated equipment, so name who refills the feeder during absences. If no plumbing route is workable, a floating dispenser avoids pipe alterations but not chemical handling or water testing; see the floater versus installed chlorinator comparison .

Safety boundaries that overrule the shortlist

Hayward specifies slow-dissolving trichlor tablets and warns that mixing chlorine products or using fast-dissolving products can cause fire or explosion. Pentair and CMP likewise restrict chemistry and warn against calcium hypochlorite in these feeders. The CDC advises storing chemicals separately, keeping them dry, and using original manufacturer-labeled containers.

Before opening any feeder, stop circulation and follow its exact depressurization steps. Do not inhale feeder fumes, substitute petroleum lubricant for the specified O-ring lubricant, or add an unfamiliar product over residue. If the feeder’s history is unknown, the label is unreadable, or the plumbing route is unclear, stop and use manufacturer or qualified installer support.

None of these feeders measures free chlorine, pH, cyanuric acid, pump flow, or bather demand. The control is an input; a water test is the result. The feeder dosing-rate verification method explains how to change one variable at a time after installation.

Methodology and limits

The model and plumbing-fit map on this page were verified on August 30, 2026, against seven sources: current Pentair records, a historical CMP brochure, manufacturer manuals and data sheets, the current Hayward Rev D manual, and CDC safety guidance, all listed below.

We did not install, operate, weigh, or test these feeders. We did not rank reliability, lid effort, long-term leakage, installer labor, local-code compliance, current price, stock, ratings, or owner satisfaction. Manufacturer pool-volume ranges and output figures are preserved as source-bounded claims, not promises for a household pool.

The useful result is a comparison of things that are often collapsed incorrectly: stored tablet mass, maximum-rated output, tested flow condition, pool-range claim, pipe fit, and service access. They answer different questions.

Sources checked

FAQ

Is Pentair Rainbow 320 an inline or off-line feeder?

Pentair identifies model 320 as inline and model 300 as off-line. The 320 has bottom-feed and manufacturer-described top-feed configurations with different published ranges, so confirm the exact manual arrangement rather than relying on the family name.

What is the difference between Hayward CL200 and CL220?

CL200 is the inline body. CL220 is the off-line route with tubing, saddle fittings, clamps, a check valve, and its own base. Several service parts overlap, but the installation hardware and water path do not.

Does the feeder with the most tablets sanitize the largest pool?

Not by that fact alone. Stored mass says how much product fits. Output and achieved chlorine also depend on tablet size, flow, run time, feeder configuration, water balance, sunlight, temperature, use, and the manufacturer’s test conditions.

Can 1-inch and 3-inch tablets use the same setting?

Do not assume so. Pentair and CMP manuals note that smaller permitted tablets erode faster in specific feeder configurations. Follow the exact manual, change one variable at a time, and verify the result with water testing.

For the named Pentair option, the Rainbow 320 review covers replacement and ongoing ownership.

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