Losing pressure when pump off

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poolnj

Gold Supporter
Jun 9, 2013
46
Need a good diagnostician ;)

When I turn off my pump to backwash, the water level by the pump strainer basket goes down, I hear a hiss from the filter, and water is rushing through the multiport valve for a few seconds. It was never like that in the past. If I wait until it stops and turn to backwash, it loses pressure completely and takes a minute or two to prime.

If I turn the multiport to backwash while I hear the water going slower but not fully stopped, it doesn't lose completely pressure and pumps right away when turning the pump back on (I know not a great idea to move the multiport before it completely stops). When in filter mode, there isn't any water going through the backwash hose which I assume would be if the multiport gasket was shot.

I cleaned out my filter which was full of DE so I know that's not the issue.

I'm in middle of opening my pool, and my filter pressure gauge is frequently getting high, if that helps with diagnosing.

The filter is definitely working, as the water is clearing up even though I didn't balance yet, but there is a ton of dirt I'm trying to deal with first (which is another reason I'm thinking it's the multi port).

Does this sound like a multiport issue, air getting into the system (or both) or something else?

Thanks!
 
duraleigh said:
When you first turn on the pump (after it being off for an hour or more), do you see bubbles or sloshing in the clear pump basket lid?
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When off, the water in the pump is empty. When I turn on the water comes in from the pool right away and primes. I do notice now a cyclone of bubbles in the pump when on. And when I turn it off, before it loses prime, I see a large bubble on the top. I'm also noticing that there is moisture around the plug of the pump. I lubed the o ring and put teflon tape on the plug, but no luck. I will get a replacement, but can that "little" thing be doing it, or is there likely air getting in someplace else?

Also, would low pressure have an affect either way on the filter pressure gauge going all the way up often, indicating it needs to be backwashed, which is happening now?

Thanks!pump-bubble.png
 
or is there likely air getting in someplace else?
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I can't be sure but it sounds like you have a suction side air leak. Somewhere between the pump and where the skimmer pipes come out of the ground.

You can also suck in air at the skimmers if the water level is too low. The multiport is on the pressure side so air cannot get in it if the pump is running.

So, if air is getting sucked into the filter the filter may be only half full of water when you start to backwash. That would account for the noises you hear when you start to backwash.

Last, having to backwash often is a chemistry issue and a separate problem. You need to SLAM your pool and get your chemistry in order. It is unrelated to the air in your system and I suggest you fix the air leak first,
 
Thanks. I am going to replace the lid of the pump which in general is aged and the plugs.

Regarding slamming, when I open the pool there's a lot of dirt and leaves even with an elephant cover. I use the big leaf sucker water hose vacuum (which I love) usually don't add chemicals first because i am backwashing often and feel it's a waste of chemicals at that point. Once it's clearer I start the slam process. Is that not correct?
 

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duraleigh said:
I still suggest finding the air leak first. The SLAM will work a lot better if your equipment is working properly. Air leaks are most always hard to find but easy to fix.
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@duraleigh thanks for your assistance. After pump was on for a while, I noticed that this joint is leaking. I'll need to get it repaired, but what's the best temporary band aid I try to apply from the outside until then, such as an epoxy, silicone, etc?


pipe-leak.png
 
That fitting is on the pressure side which are generally not very receptive to external repairs since the water is pushing out. You could shut the system down for a while and try an epoxy giving it time to set, but there's no guarantee it will last.
 
Texas Splash said:
That fitting is on the pressure side which are generally not very receptive to external repairs since the water is pushing out. You could shut the system down for a while and try an epoxy giving it time to set, but there's no guarantee it will last.
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I picked up JB Water Weld which had mixed reviews, but it worked really well as a temp fix. I also replaced the pump lid. When I had the backwash issue, I heard water coming back from my Hayward chlorinator. I likely need a new check valve for that but I turned that off also. Not sure what exactly did the trick, but my pump is working perfectly now and there is no air at all, and doesn't lose pressure. There was obviously a lot of sand returning to my pool when I had the issue, because my robot was running non stop and the bottom was still full of sand.

I didn't even add any borax or baking soda to my pool yet - just chlorine - and 2 days later, my pool has no sand and is sparkling!

Thanks all for your help!

PXL_20230530_000404299~2.jpgpool.jpg
 
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