Return flow slows down within hours

ls007

New member
May 25, 2016
2
Westford/MA
This is the first season I opened the pool myself. I am making progress on turning the green swamp to a crystal clear pool, green color is gone and I can see the bottom of the pool but some cloudiness remains. Progress has been slow due to the equipment working in a funny manner. The symptom is that the return flow rapidly slows down in a matter of hours. My interim solution has been to turn the pump off, open the bleed valve until air intake stops audibly, restart the pump let the filter fill back up with water and close the bleed valve. This process seems to get the flow back to the normal level until it goes down again. Initially I suspected dirty DE filter fabric so I disassembled the filter and hosed off the filter grids. However this has not helped. The other reason I do not think it is a clogged filter is because the backpressure is staying constant at around 18 psi. In my view a clogged filter would lead to increased backpressure over time. I am also suspecting debris in the impeller. I tried to clean the impeller by hand and through a wet vac but have not tried to fish out any debris using a coat hanger hook though. I am down to my last 2 options
1. another try at cleaning the impeller
2. chemically clean filter grid using TSP

Any other suggestions before I break down and call the pool guys?

Thank you
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,932
San Dimas, CA (LA County)
Pay attention to the pressure gauge. As the flow slows, the pressure is going up. Or should be unless the gauge is broken.

What's happening is that your filter is working. As it strains out stuff, it clogs and the flow drops and the pressure rises. When you let it bleed down, you're causing the algae and DE to fall off the grids. That's pretty much what the bump-type DE filters do. Your filter should be backwashed and recharged with DE. You want to get that stuff out, not just rearranged.
 

ls007

New member
May 25, 2016
2
Westford/MA
Pay attention to the pressure gauge. As the flow slows, the pressure is going up. Or should be unless the gauge is broken.

What's happening is that your filter is working. As it strains out stuff, it clogs and the flow drops and the pressure rises. When you let it bleed down, you're causing the algae and DE to fall off the grids. That's pretty much what the bump-type DE filters do. Your filter should be backwashed and recharged with DE. You want to get that stuff out, not just rearranged.
Hello,
Thanks for the quick response. In previous years I have clearly seen the correlation between pressure and flow rate. However, that's not what is happening. I have tried backwashing multiple times even though the pressure is not changing and that has not helped. I do not believe my gauge is broken based on how it has responded to fixing leaks. Having said that, I am going to try and backwash again and also perhaps clean the grids with TSP. Any other suggestions are welcome.