DE backing up into pump housing

[HenderPool]

Hello,

Last summer, I had my pool equipment moved 28 feet + 3 feet up in elevation. We had some trouble getting it to maintain prime initially, so they installed a check valve before the pump, which worked well for a bit. Pictures of the equipment are below (note one was taken before we installed the check valve).

Recently, I noticed an air bubble in the filter, I opened the housing, and then found it would not prime again. A local company took a look, cleaned the filter, and replaced the fingers on it. That seemed to do the trick and it's been running fine for 7-10 days.

2 nights ago, my wife noticed it had lost prime again and there was some DE in the pump housing. This surprised me because I know the filter pressure had been looking good. I took the filter apart, removed all DE, cleaned the fingers, and reassembled. It primed fine, and was running well initially for 40 minutes or so. I added DE and it seemed ok initially. Woke up this morning and it had lost prime, with DE in the pump housing again.

Any idea what could be happening here? Is this a new problem, or something systemic that the pool company that replaced the fingers did not address originally when they were here 2 weeks ago? If it's not something I can fix myself, any suggestions for managing the pool from now until when they can take a look (Wednesday next week).

 

[PoolStored]

DE coming back into the pump housing is because there is no check valve between the pump and filter to stop it. Not a worry, when the pump starts again, it will push it back into the filter.

The first assumption, when a pump loses prime is that you have a suction side air leak. In the pipes, or in the check valve or diverter valve.

Run the pump for a while and watch it for 15 minutes to see if air is getting in the pump strainer lid. If you can see air coming in, run a hose over the check valve, then the diverter valve. If that stops the air bubbles, then you need to rebuild the check valve or diverted. If that doesn't fix it you have a leak somewhere else on the suction side.

My recommendation:
Get some silicone lubricant like Magic Lube II (not ptfe/teflon lube)
Remove the pump lid, clean the mating surface on the pump basket, clean the lid, inspect the o-ring for cracks, re-lube and assemble. If o-ring is cracked, replace it.
Do the same for the pump drain plug o-rings.
Then do the water test above...or just order replacement o-rings for the check valve and diverter valve and rebuild.
After that, if is still a problem, it is likely in the suction pipes.

Suction Side Air Leaks

If you see air bubbles coming out of the return lines in your pool, you likely have a leak. Some signs that a suction side plumbing leak has occurred include: Read more

www.troublefreepool.com

 

[HenderPool]

Thank you for the reply. I implemented the steps you listed above. At first the pump would not prime, but then I was able to get it going by opening the air bleeder on the filter. I ran the pump for about three hours then turned it off. I came out and hour after that and it had lost prime, but I was able to get it going in the same fashion.

Why might I be losing prime each time the pump turns off? Does this still indicate a suction side leak? The fittings and pipes are all new as of last season so that would be surprising to me.

 

[PoolStored]

I implemented the steps you listed above.

Did you rebuild the check valve and diverter?
Did you read the suction side leak article?
What exactly did you implement?

So, we fixed the ability to maintain prime while running and are now faced with inability to maintain prime when off...correct?

If that is true, you likely have solved the suction side...maybe.

If you have no visible water leaks on the pad, you still likely have a suction side air leak.

Only way for the pump to lose prime when off is if there is a leak somewhere that allows the air into the system. It could be on the suctions side (pump lid, etc) or on the pressure side (like a filter fitting). The pressure side leak is not always obvious because it may not let water out when pressurized, but could let air in when the pump shuts off, but this is rare. Check the air bleeder valve on the filter.

I'd also check this valve out. These valves can be very leaky. I'd consider replacing with a ball valve:


I suggest you get it primed, then turn off the pump and see if you can hear air getting sucked in anywhere.

You need to stay there for the 30 minutes and try to figure out what is going on.

 

[1poolman1]

Thank you for the reply. I implemented the steps you listed above. At first the pump would not prime, but then I was able to get it going by opening the air bleeder on the filter. I ran the pump for about three hours then turned it off. I came out and hour after that and it had lost prime, but I was able to get it going in the same fashion.

Why might I be losing prime each time the pump turns off? Does this still indicate a suction side leak? The fittings and pipes are all new as of last season so that would be surprising to me.

What kind of check valve was installed in the suction line? If it wasn't a spring-loaded one, or something is not allowing it to completely close, it is still allowing water to flow back to the pool through the pump which has to come backward from the filter. That's the only way D.E. can get back into the pump, water flowing backwards when it is off. A pump that high above water-level can have these type of problems.
A pump that high is also sucking "harder" as it has to lift the water higher. Any tiny air leak will be made a bigger problem as it is much easier for a pump to pull air than water and the higher vacuum will cause a minor suction leak that you normally would not worry about to be a larger issue.

 

[HenderPool]

Update:

1) I had done everything you suggested from "Run the pump" until the end of your reply.
2) It looks like I only lose prime when the pump is off for several (4-6) hours.
3) there does appear to be a very small water leak from the valve you identified. Could that be causing this? I will plan to order the ball valve and replace.
4) the other thing I notice is that there is a gurgling sound from the filter when I turn the pump off.
5) not sure if this is normal, but I have a return line and the skimmer line. I've noticed that I can prime it if turned to the skimmer only, but not when both are open. If the pump is on, I have to open the return line very slowly or else I lose prime.

Thank you for your input.

 

[HenderPool]

What kind of check valve was installed in the suction line? If it wasn't a spring-loaded one, or something is not allowing it to completely close, it is still allowing water to flow back to the pool through the pump which has to come backward from the filter. That's the only way D.E. can get back into the pump, water flowing backwards when it is off. A pump that high above water-level can have these type of problems.
A pump that high is also sucking "harder" as it has to lift the water higher. Any tiny air leak will be made a bigger problem as it is much easier for a pump to pull air than water and the higher vacuum will cause a minor suction leak that you normally would not worry about to be a larger issue.

It is spring loaded but I see what you're saying. I will try to fix the small leak from that valve, and if that doesn't work, perhaps open the check valve and try to reseat it? The oring on it has already been replaced I believe by the pool company that came originally.

 

[HenderPool]

Just a note to say this was due to a faulty check valve between the pump and filter, in case anyone else has a similar problem