Skimmer Evacuates when pump shuts down

foamfoot

Member
Jun 22, 2022
6
Oakland, CA
Pool Size
13000
Surface
Plaster
Chlorine
Liquid Chlorine
Hello, Ive seen a few threads on this from many years ago so I wanted to create a new one. First, I have solar heating with the panels on my roof so this may (or may not) be complicated you are the experts! My issue is that when the pump turns off water rushes backwards into the skimmer and then sends all the debris back into the pool. I assume I need some sort of check valve between the pump and the skimmer pipe/line. Is this correct? Any product recommendations for this type of valve? I see a few but do not know enough to select one.

Thank you!
 

1poolman1

In The Industry
Jul 14, 2014
1,578
Sacramento
Does it only happen when the solar has been on? A check valve after the filter would stop it. If it happens all the time, a check valve in front of the filter would stop it. Or just put one in front of the filter and the water will have to go to the returns.
 

foamfoot

Member
Jun 22, 2022
6
Oakland, CA
Pool Size
13000
Surface
Plaster
Chlorine
Liquid Chlorine
What is weird is I have a check valve already after the filter and it doesnt stop it. I think the heat is on when the pump goes off. Its not a sophisticated heat panel so "auto" generally means always on.

What I notice is that when the pump goes off the water in the visible part of the pump drains out through the skimmer pump if that makes sense (ie the water where the pump basket is located). Sorry I am new to pools and trying my best. Thank you!
 

1poolman1

In The Industry
Jul 14, 2014
1,578
Sacramento
What is weird is I have a check valve already after the filter and it doesnt stop it. I think the heat is on when the pump goes off. Its not a sophisticated heat panel so "auto" generally means always on.

What I notice is that when the pump goes off the water in the visible part of the pump drains out through the skimmer pump if that makes sense (ie the water where the pump basket is located). Sorry I am new to pools and trying my best. Thank you!
Picture of your system would help. I'm guessing that the heat "on" light is on a solar control. That would indicated that the valve is in the solar "on" position when the pump shuts off. If the check valve after the filter has failed you will have what you are experiencing.
 

foamfoot

Member
Jun 22, 2022
6
Oakland, CA
Pool Size
13000
Surface
Plaster
Chlorine
Liquid Chlorine
Correct assumption here. When the solar heat light is on when the pump shuts off and remains in the on position. Its an older system unfortunately.

Here is a picture. I have the Jandy Valve that automatically opens/shuts when solar heat is on/off. Then I have that check valve on the outlet side of the pool filter if that makes sense. Any recs from here are appreciated!
 

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1poolman1

In The Industry
Jul 14, 2014
1,578
Sacramento
If your valve is in the "solar off" position (which it appears), the way the system is plumbed your panels always have a water going to them unless there are two isolation valves. I only see one, blued handle, and that won't stop water from filling the panels by itself with the pump running. If the pump turns off with the solar valve in that position, water will fall off the roof and cause what you are seeing. Solar should always be plumbed so that all water to the panels can be stopped.
 

foamfoot

Member
Jun 22, 2022
6
Oakland, CA
Pool Size
13000
Surface
Plaster
Chlorine
Liquid Chlorine
Yes, it has two blue valves for the roof solar I just didnt include in the previous picture (updated below). They remain open during the season and closed when we drain for the winter. This does not appear to be related to my question though...?

The Jandy Valve automatically closes when the heater is off. However, the skimmer still floods when the pump turns off. Do I need a check valve between the pump and the skimmer? I guess this because the behavior I see is when the pump turns off all the water in the strainer pot area releases backwards into the skimmer line and the skimmer ejects water thus ejecting all the debris for the day. Your help and insight is greatly appreciated!
 

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1poolman1

In The Industry
Jul 14, 2014
1,578
Sacramento
Easiest way to find out if it is filter pressure causing this is to remove one cartridge from the tank, run the system for a brief time and then turn it off. If the water doesn't act the way you describe it is the system releasing pressure backwards through the pump and causing the issue. Since there is already a check valve between the filter and pump that would mean it had failed and needs replacing. I didn't notice that valve before as I was concentrating on the solar plumbing.

It looks like that white check valve was added after the initial install because this was a problem in the past. Never liked, nor used, a check valve that didn't have an easy way to remove, inspect, or replace. That one will have to be cut out to be replaced.
 

foamfoot

Member
Jun 22, 2022
6
Oakland, CA
Pool Size
13000
Surface
Plaster
Chlorine
Liquid Chlorine
Fascinating. I did not realize that there were multiple check valves. In addition to the black one I identified already on the outlet side... is the red circle the check valve you mention or is it the blue circle? Im not familiar with these styles. How easy is it for a DIYer to replace this if that is the issue?
 

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