Pentair IntelliChlor

Two different product lines carry the IntelliChlor name, and the cells do not swap between them.

IntelliChlor IC15, IC20, IC40 and IC60 is the long-running line, and the one this page is mostly about. The cell plumbs inline and — on everything except the IC15 — runs off a separate PC100 power center.

IntelliChlor PLUS and LT is the newer line: PLUS30, PLUS40, PLUS60, LT15 and LT25, with their own controller assemblies and their own cell numbers in the 5237xx range. They share the union kit and the PC100 with the old line. The PLUS40 and PLUS60 are the same length as this cell; the shorter LT15, LT25 and PLUS30 come with a retrofit adapter, 523101, to fill plumbing cut for an IntelliChlor.

So "an IntelliChlor cell" is not a thing you can order. The model on the label is.

Sizing it, and why bigger is the normal answer

Pentair rates each cell two ways, and the second one is the useful one:

• IC15 — 15,000 gallons, 0.60 lb of chlorine per 24 hours
• IC20 — 20,000 gallons, 0.70 lb per 24 hours
• IC40 — 40,000 gallons, 1.40 lb per 24 hours
• IC60 — 60,000 gallons, 2.0 lb per 24 hours

Those pound figures assume 24 hours of continuous pump run time, which nobody does. Run eight hours and you get a third of it.

That is the whole argument for fitting a cell rated well above your pool. An IC40 on a 20,000 gallon pool is not oversized — it is a cell that will hold the pool at a lower output percentage, which is the setting that decides how long the cell lasts. Cells wear by generating, so the same chlorine made at 40% output costs less cell life than at 90%. The extra money at purchase buys years at the other end.

The salt calculator works out what to add to reach a target, and the wider salt system guide covers the trade-offs of going salt at all.

Pentair's manual disagrees with itself about salt

This one is worth knowing because it explains why owners get contradictory advice, and the contradiction is inside a single Pentair document.

The English water chemistry table in the IntelliChlor manual gives 3,600 to 4,500 ppm, ideal 3,600. The Spanish table on a later page of the same manual gives 3,000 to 4,500 ppm, ideal 3,400. Same document, P/N 520589 Rev. R.

Meanwhile the cell's own salt LEDs describe a third band: green for 2,800 to 4,500, red below 2,800, and the cell shuts off entirely below 2,600 ppm.

For a US owner reading the English section, 3,600 ppm is the number to aim at — and it is higher than the 2,700 to 3,400 range quoted for salt systems generally, including elsewhere on this site. If your cell is Pentair, use Pentair's figure rather than the general one.

Two practical notes from the same manual. The cell's salt reading is accurate to ±500 ppm, so it is a guide rather than a test kit. And after adding salt, run the pump 24 hours before testing — readings taken before the salt has dispersed are meaningless and are the usual reason people overshoot.

It stops making chlorine every winter, on purpose

The temperature sensor switches the cell off below 52°F, plus or minus 3°F, lights the COLD WATER indicator, and produces nothing until the water warms.

This is protection, not a fault. Generating in cold water damages the cell. But it catches people out every spring and fall: the pool is open, the pump is running, the cell shows a light, and chlorine is not appearing. In shoulder season, a salt pool needs liquid chlorine — the cell is not going to do it, and no setting will override the cutoff.

It also means a cold-water light showing in July is a real fault, and the temperature sensor lives in the same assembly as the flow switch, which is the part to replace.

Cyanuric acid: what Pentair says, and what this site says

Worth setting out plainly, because the two differ and the difference is deliberate rather than an error on either side.

Pentair's manual says to keep cyanuric acid between 30 and 50 ppm when using an IntelliChlor. That is the manufacturer's instruction for this cell, and if warranty conversations matter to you, it is the number in writing.

This site's general salt guidance suggests 60 to 80 ppm on a salt pool, on the reasoning that more stabilizer protects the chlorine the cell makes, so the cell runs at a lower output percentage and lasts longer. That reasoning is sound and widely used, and it is not what Pentair prints.

Both positions are defensible. What is not defensible is following one without knowing the other exists, so: the manufacturer says 30 to 50, the longevity argument says higher, and the trade is cell life against staying inside the printed spec. Do not use cyanuric acid at all in an indoor pool — on that, there is no disagreement.

Fit it in the right place, and run the dummy cell first

Two installation rules from the manual that are easy to get wrong and expensive to fix.

At least 5 feet from the inside wall of the pool, which is an electrical safety requirement rather than a plumbing preference. And at least 3 feet downstream of the heater outlet, because water leaving a heater is hotter than the cell is built to sit in.

On a new pool, fit the pass-through cell, 520588, for the first thirty days. It completes the plumbing and generates nothing, so plaster dust and construction debris go past the cell rather than through its blades. The real cell goes in afterward. People skip this because the cell they paid for is sitting in a box on the pad, and it is a costly thirty days to save.

When output drops, check three things before buying a cell

The cell is the expensive part, and it is not usually the first thing that has failed.

The usage hours meter, which is built into the unit and reports lifetime hours. A cell at the end of its service life and a cell that is merely scaled look identical from the deck, and the meter tells them apart.

Scale on the blades. The cell self-cleans by reversing its polarity on a cycle, which limits calcium buildup rather than preventing it. On hard water it still needs an acid clean by hand, and the kit — 520670 — is a cap that lets you stand the cell in solution. Wear gloves and eye protection, add acid to water and never the reverse.

The flow and temperature switch. One assembly, both sensors, and the single most common thing that stops a healthy cell working. Pentair publishes a replacement guide for it, and the kit is a fraction of a cell.

If all three check out and the salt is genuinely at 3,600, then it is the cell.