Help with Pentair IntelliChlor IC40 not producing Chlorine


New member
Sep 10, 2021
Hello everyone,

Seeing if I could get some help troubleshooting my Pentair IntelliChlor IC40 salt cell.

It was replaced back in March 2018 (just the cell, the power supply is original one from 10 years ago) and now it's not producing any chlorine. All the lights are working as normal and my latest water test from Lesile's reads;

Lesile's test from today (also attached scan)

Free Chlorine 0.34
Total Chlorine 0 .4
pH 8.1
Total Alkalinity 54
Calcium Hardness 237
Cyanuric Acid 5
Iron 0.1
Copper 0
Phosphates 0
Salt 4062

Pool Size is 15,500 gallons

NOTE: I cleaned my Pentair fiberglass cartridge filter over the weekend, but that did not help.

Does anyone have any suggestions? Thanks in advance my friends :)


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Gold Supporter
TFP Guide
Jun 16, 2019
Hey MX !!! *if* the pool store is even close with your CYA…….. IF……. Then you have none. Any FC you add will be gone in a couple of hours. Maybe even 45 mins. So chances are your cell is doing just fine but you aren’t protecting its output.

The FC/CYA Chart is the Bible here and must be followed religiously if you want to be trouble free. To do so you need your own reliable testing. The kit costs a fraction on *one* trip to the pool store and will pay for itself literally dozens of times.


Gold Supporter
May 20, 2020
Katy TX
Pool Size
Liquid Chlorine
I am in Houston area and lose about 3-4ppm per day of FC. I have my CYA at 50. So if you have basically zero CYA (noted as 5 on the test) then you are losing your chlorine as fast as you are producing it. My assumption is that the SWCG is set to replace what you lose each day. You should purchase some liquid chlorine to raise your FC quickly and also purchase stabilizer to raise your CYA - ideally to about 60-70. That way, you bring your FC up to the desired level of 4-6ppm and then your SWCG can be adjusted to maintain it at that level throughout the day.
Please review FC/CYA Chart and also consider purchasing and subscribing to the PoolMath app.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

As a general rule, if the lights are working, the cell is making chlorine..

Look at the "Cell" light and see what it does.. It will be green when the cell is producing chlorine, and off when not producing chlorine. If the cell is set for 50% output, the cell light will be on for about 2.5 minutes and off for 2.5 minutes.

What output % are you running and how long per day are you running the pump?

I assume the Flow light is green, the salt light is green.... ??

As other have pointed out, if your CYA is actually zero (5 ppm) then the sun will eat any chlorine that you cell produces pretty quickly.. And.. with an FC of less than one, you more than likely have an algae bloom, even if you can't see it yet.. No cell can make more chlorine than algae can consume.

You need to get some Liquid Chlorine in your pool ASAP..


Jim R.


New member
Sep 10, 2021
Currently have the cell set in boost mode and flow and salt light are both green. I will try some liquid chorine and see it that helps.

I will look into the app too :)

Thanks for all the suggestions! You guys are awesome!


Silver Supporter
Jul 29, 2018
"Old" Katy, TX
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
When you have your own test kit, try collecting some water at a return nozzle and test it for FC. I'm in the Houston area. Running my IC-40 at 20% right now, and it still is holding FC at 6.5. CYA is at 70, although until this week it was only 60 and stayed at 6-7ppm range with the IC40 at 40% (sun was higher in the sky, though, too.)
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