Losing water & possible sand filter pressure leak

[flygirl516]

We have a lot of issues with our pool that I think (hope) are related:
1. We've been losing about 1/2 inch water a day. This happened last summer too, we dug up the pool lines we could access and had someone check for leaks in the pool. Couldn't find anything substantial.
2. When the pump turns off, the pump basket empties and it sounds like the water is rushing out of the sand filter. When it turns back on, it takes 2-3 minutes for the water to pull back through the pump.
3. When we backwash, some water dribbles out of the ring below the valve, as well as the clear glass. We've tightened as much as we can with tools.
4. It sounds like a slight whistle from the glass and valve, the psi sits at 11 which is slightly lower than usual.

I've read a bit on here, and it perhaps could be the spider gasket, but I'm not sure where to start the trouble shooting. I also don't know how we can be losing so much water a day. The dirt is wet under the sand filter, but again, not THAT much water. The pump & filter sit above the pool water line (I saw that asked a few times)

Since I don't know exactly what's going on, I've been guessing search terms for the forum. Spider gasket issue was the one I saw the most. I appreciate any help! Thanks!

 

[mknauss]

Can you see the exit of your backwash outlet? Or is it plumbed into the sewer or other underground system.

 

[flygirl516]

Yes I can see it. We have a backwash hose into the woods behind our house

 

[mknauss]

Make sure nothing is coming out of it when set to Filter.

 

[flygirl516]

There is nothing coming out the top when set to Filter. There is a slow dribble when backwashing.

The pump shut off for the day and my husband said that the pump basket was only 1/2 full of water and it sounded like bubbles in the sand filter. By the morning, the water will be low enough in the pump that it'll take a few minutes to prime and run again.

I found a pool school article that takes apart the sand filter valve up top. We can take that apart tomorrow and check everything.

 

[wireform]

For starters you need to get a new O ring for the MPV and unscrew the sight glass and put some Teflon tape to get a better seal.

 

[flygirl516]

Will do. We have teflon on the sight glass but husband says we could do more. We'll also pick up an O ring tomorrow to replace when we check out the valve.

 

[flygirl516]

This morning I noticed the dirt is soaked under the concrete pad the filter sits on. Is it possible the bottom of the filter is leaking? There is no water on the concrete of itself

 

[wireform]

Anything is possible you need to Investigate.

 

[Kidswimin]

I have the same issue, but no water loss that I can tell. I bought a new MPV last year (generic) as mine was old and worn out. It worked great last year. I just opened the pool last weekend, and thought everything was good. When I went to start the pump in the morning, it was empty and needed to prime. That has never happened in the past.
When I shut off the pump, I could hear a whistle, sucking in air, but I thought it was the solar panels draining. I've been keeping an eye out for leaks, and haven't noticed any. Every morning the pump is empty.
Last night, I noticed a small leak looked to be from the gauge not tight enough or not enough tape on the threads. I pulled it off added some tape and reinstalled. Started pump, and leaking worse. Took a closer look, and the generic MPV has a crack right above where gauge screws in.
Last night I put on some JB weld. This morning I started the empty pump, and the weld was better, but still leaking.
This morning I ordered a Hayward replacement.
Look for hairline cracks.
Hope this helps.

 

[flygirl516]

OK I think I need to redirect my question - please let me know if I should start a new thread!

We noticed that the water pressure from the far return was much lower than the close one. We decided to test them one at a time.

- When both returns are on, filter PSI is 11 and there is a bubbling noise in filter. Far return is much lower pressure.
- When close return is on only, filter PSI is 11 and there is a bubbling noise in the filter, water pressure is high/normal.
- When the far return is on only, filter PSI is 15 and the bubbling noise is gone, water pressure is high/normal, much higher than when both returns are on.

I assume this means there is air entering the line between the filter and the close return? We visually inspected the lines, there is a blue glue that I don't see any gaps.

We added Teflon to the sight glass, tried to replace the gasket O-ring but it caused a lot of leaking out the top so we put the old one back on. The bracket that holds the MPV to the filter has a tiny gap but since the whistling/bubbling goes away when we switch to the far return only, I don't think that's our issue. I'll check for hairline fractures too. Any tricks to check for cracks/gaps? I read that if you put some water and it sucks in, that it can help ID a gap, but I'm not sure if that's a tried and true method.

We also measured the pool level to see if we lose water with just the far return on. We have it running on the one return (far one).

thanks!

 

[flygirl516]

I think we found the leak!

So we weren't able to see anything come out the backwash hose, so we removed the hose entirely and sure enough, it's a steady stream of water when in Filter mode. I'm optimistic this is our issue! Tomorrow, we will remove the valve from the filter and inspect to see if anything appears out of place. My husband had tried to disassemble the valve last year and perhaps something is not sitting right inside. (just found that one out!)

If something isn't right, or it's still leaking, I plan to buy a new valve.