Low flow & salt cell not working

SDPadres

Member
Jul 6, 2024
18
San Diego
Pool Size
16500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I had pool solar heating installed a few months ago and while they plumbed it I had the pool guy install a backflow valve between the heater and the IC40 salt cell. Recently I noticed the salt cell is not producing chlorine because the flow light is red. I thought it was because of all the elbows he installed and not enough straight plumbing below the salt cell. He came back to replumb it and he told me the neat solution was to move the salt cell and he installed it upside down but said it wasn't a problem because the water is flowing in the right direction. The red flow light is still on. He told me it's my flow sensor but my IC40 is only 11 months old. I'm calling pentair on Monday but thought I'd get advice here. The RPMs are set at 2600 when in pool mode but I do notice the return lines have little pressure. When the pool solar is on the return line pressure is really good but right now I have the solar turned off because I don't want the pool to be warm in the summer. If I raise the RPMs on the pool pump the flow light will sometimes turn green but then turns red again. Here are some pictures of how the cell was plumber before and how it is plumbed now.
Thank you,
David
 

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Welcome to TFP.

What model pump do you have and what RPM is it running at?

What model filter do you have?

What is your filter PSI?

When did you last clean your filter?

Sounds to me like you have a dirty filter that is slowing the flow.
 
I have a Pentair Intelliflo Variable speed pump that was installed in 2014 that is currently running at 2600rpm.

The filter is a Pentair FNS P60 Fiberglass DE and my PSI is 20. I cleaned the filter a little over a month ago.

Thanks for your response.
 
What heater?

20 PSI sounds on the high side for 2600 RPM.

Backwash your filter and see what the PSI drops to.
 
Pentair Master Temp 400. Could the high PSI be caused by adding too much DE. I got it pretty close to the recommended 6 pounds. I will try backwashing. Thank you.
 
Could the high PSI be caused by adding too much DE. I got it pretty close to the recommended 6 pounds. I will try backwashing.

You add 6 lbs of DE with a totally clean filter.

You add 5lbs of DE after a backwash.
 
I have never backwashed. I just open it up and clean all the grids every 3 months. I will try the backwash and add the 5lbs tomorrow. I hope that works. Ideally what should my PSI be at?

Thanks again.
 
I am looking for 16-18 PSI but it depends on your plumbing setup.

What happens when you crank your pump up to 3400 RPM? Does the red flow LED go out? What is the PSI?
 
I haven't tried 3400 yet but when I tried 3000rpm the PSI goes up to 30 and the flow light turns on temporarily but eventually goes back to red.
 
I haven't tried 3400 yet but when I tried 3000rpm the PSI goes up to 30 and the flow light turns on temporarily but eventually goes back to red.

That all indicates the flow switch is working properly and your filter is clogging, likely with algae, as the pump runs and flow slows.

Can your pool Rear a Overnight Chlorine Loss Test?
 

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I haven't seen any algae in my pool and I keep my water balanced but it's possible. I'll do the backwash tomorrow and if that doesn't help I'll open the filter and clean it up. I hope that solves the issue.
 
I don't have the water test kit required to do the OCLT but I'm going to order one. I'm thinking I will need to SLAM my pool. I added 64oz of chlorine yesterday evening after the sun went down and I have less than 1ppm today. Should I clean my filter first and then SLAM or do I clean it after?
 
Clean it before and during. When your clean pressure rises 25%, clean it again. You may be cleaning often during SLAM.
 
64 oz of 10% liquid chlorine will only add 3 ppm of FC to the pool. Your pool is likely burning 3 ppm of FC daily.

For now, add 4-5 ppm of FC daily until your test kit arrives. That's about 96 oz of LC. This will help keep the pool stable until you get to the Overnight Chlorine Loss Test.
 
I'm using 12.5 % liquid chlorine. According to the Orenda calculator every 16.9 ounces is giving about 1ppm so I think about 85oz should get me to 5ppm.

I noticed that now my pool heater isn't working either, I'm assuming because of the low flow. The red service system light turns on. I'm hoping after I clean the filter today I get more flow.

Thanks for the help!
 

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