Hydrostatic Relief Valve Leaking?

[alam2p]

My pool is losing ~1” of water a day and has now gone past the skimmer, so I know it’s not that… main drain is plugged too so that can’t be it. I haven’t yet ruled out return-side leaks, but in the meantime, I’m wondering if it could be a hydrostatic relief valve… Pool professionals have been too busy to come by right now.

It’s an in-ground concrete pool, 23k gal - last I checked, I didn’t think I had an HRV (just looked like a big round plug that didn’t look like it could spring open, but what do I know?) but looking at low-res plans left behind and reading around, it seems unlikely that a concrete pool would omit that. I plan on diving down to take a closer look at it later.

In the past, the pool has lost lots of water and just stopped - I’m theorizing that it’s because the leak may have brought the water table to a similar level (I live on a hill, approx. 100m above a lake, so I’m not sure if that’s even possible). I’m not certain, but I don’t think most leaks just “stop” leaking for a month so I’m reframing my mind to think outside the box and exploring possibilities.

The pool is always covered when not in use but no matter what, there is always dirt-like debris at the bottom of the pool. There are little cut-outs in the solar cover for pool steps, etc, and I never really gave it any thought, but does that sound symptomatic of a relief valve issue letting small debris flow back into the pool? The water is pretty clear and clean around the main drain, though.

I’ve read that vacuuming can cause the valve to partially be stuck open because of sand, pebbles, etc. If I recall correctly, I did bring the vacuum head over the main drain cover to catch a leaf, so maybe that did it…

This is driving me crazy, so any opinions or comments would be appreciated, thanks!

 

[Texas Splash]

HRVs can move just enough to allow very fine debris to get trapped preventing a good seal. At the same time, some valves simply go bad over time. There are a few videos of them being changed on YouTube. If you can dive down long enough with a syringe and some food dye you might be able to confirm if water is seeping out.

 

[alam2p]

Well, I took a chilly dive and while I didn't have any dye testing stuff with me, I did confirm something and also discovered something...

Confirmation: I don't think I have a hydrostatic relief valve. It looks to me like an oversized octagonal plug that doesn't move. Has anyone seen anything like this?



Discovery: While struggling to maneuver around underwater, I also came across a crack in the main drain housing and I'm wondering whether this might be the cause of all my problems. Assuming this is the leak, how hard is this to fix underwater? Would underwater epoxy work?

 

[Texas Splash]

Looks like both lines may have been plugged in the past. Perhaps some A&B Epoxy might serve you well on the drain housing crack.. What do you think @Poolbreh?

 

[Poolbreh]

AB epoxy should work aka pool putty. I think you need to continue to let the water drop, I think it could be a return. If it’s possible isolate returns or turn pump off. If it’s the returns it may be best to get a leak detection company out.

 

[alam2p]

thanks for the reply! The pump has been off for a few days now as the water is below skimmer and main drain is plugged and the water keeps dropping. I plugged the wall returns before work this morning and put a bucket of water on the steps. It seems like the loss in the pool is still greater, although today was quite a windy day.

There are in floor returns that could be an issue but I don’t know how to isolate that.

 

[wireform]

If you can dive down there why guess. Take some food coloring and do the test around the main drain.

 

[alam2p]

There is a slight bulge at where the crack is, so I'm wondering whether epoxy is going to last for a long time. I don't have any other alternative so I'll give it a try anyway, but is there a more lasting solution that professionals would use? I don't know for sure how main drains are installed but I thought they are supposed to be encased in concrete.

Could a bulge be an indication that there's something on the other side exerting pressure on it (ie, ground water)? I have a hard time believing that this is due to "aging" of the main drain. Could this be due to the fact that I don't have a hydrostatic relief valve to relieve groundwater pressure?

 

[wireform]

Looking back at the picture of the two plugs it would seem to me the plug on the side port isn't seated properly as the gasket is in full view not compressed and if you look carefully you can see Teflon tape hanging out too. Those plugs don't need Teflon that's why they have a gasket. I'd put money on it that's is your leak if you think its at the main drain.

 

[alam2p]

I put that in myself . I didn't know how hard to crank it so I just went hand-tight. When I go for a chilly dive again, I'll give it a stronger twist.

 

[wireform]

Before you touch it test with the dye to know what you had or didn't have going on there. If that's the leak then once you do what you need to do the dye test will be the deciding factor so you can call it fixed.

 

[Bperry]

I put that in myself . I didn't know how hard to crank it so I just went hand-tight. When I go for a chilly dive again, I'll give it a stronger twist.

The threads on gasket style plugs like that are usually not tapered for Teflon tape. I’d find out for sure and use the right plug or at least test it with dye. Threading a plug in tighter than is capable might crack the housing.

 

[alam2p]

I went for a swim again today with some food colouring and I feel the results are inconclusive. I didn't see the dye getting sucked out in a way that would indicate a leak (including by the returns, in floor returns, main drain... didn't test skimmer as water is still well below that). Obviously there is a leak, but I'm wondering whether I was moving around too much to make it a conclusive result.

While I was down there, I did give the plug a little more tightening without the teflon tape. I'm suspecting that it might not be a main drain plumbing issue as I did un-do the plug and put some dye there as well. Didn't get sucked in.

While I was down there, I put some epoxy putty on the crack anyway. Perhaps psychologically, I thought the dye dissipated quicker there but it definitely did not flow the way I've seen dye tests flow online. I figured that for a few dollars, I can't go wrong patching a crack that's obviously not supposed to be there. If that is the source of my leak, I hope that I did a good enough job...

 

[wireform]

Being down there pushing the water around is probably not a workable solution for a dye test.

 

[alam2p]

Being down there pushing the water around is probably not a workable solution for a dye test.

Yeah I figure that as well... just don't know how to do it while holding my breath and trying to get close enough to observe

 

[alam2p]

Well that didn’t work. Woke up to another 3/4” loss in approximately 12 hours. Time to try and find some experts and hope they’re available to come in… A little discouraging given the hellish swim yesterday

 

[Bperry]

Well that didn’t work. Woke up to another 3/4” loss in approximately 12 hours. Time to try and find some experts and hope they’re available to come in… A little discouraging given the hellish swim yesterday

I have a company coming in Monday to do a full inspection and leak location.Looks like they have lots of locations. If they work out and aren’t sheisters, I’ll send you the info.

I have a similar leak issue though not as much water loss. Leaks the same 1/2” per day with the pump on or off. I even plugged the returns and skimmers to isolate the plumbing and the shell and have the same loss, which points to a main drain or a shell leak. You might try something similar for free before calling someone.

 

[alam2p]

Well this is kind of amazing...

Before I left for work yesterday, I went down to the equipment room and shut off all the valves, set multiport valve to closed and gave the backwash line valve an extra hard twist. To my surprise, it held water just fine all day, so when I came back from work, I filled it up again to the tile line and left it overnight.

It held water!

My theory now is that the water must be gravity draining through the system and going out the waste line somehow (all my equipment is below waterline). I never considered this a possibility because it's a brand new filter - I've used it about a month and maybe used the backwash function twice. Each time, I've taken extreme care to make sure the pump is shut off, water is no longer running, and to fully depress the multiport handle before turning it. A leaking line was a problem with my old filter, but I didn't think a brand new filter would have the same problem; that's why I didn't even consider looking at it.

The pool has been holding water overnight so that's already a huge win. I'm just glad we're on the winning side for once.

I have a similar leak issue though not as much water loss. Leaks the same 1/2” per day with the pump on or off.

Good luck on your battle. I can empathize that this is not all that much fun...

 

[alam2p]

I went down to the equipment room and shut off all the valves, set multiport valve to closed and gave the backwash line valve an extra hard twist. To my surprise, it held water just fine all day, so when I came back from work, I filled it up again to the tile line and left it overnight.

To all the experienced members here, I'm keen to rule out a pipe or structural issue since the pool held water without a problem when all the valves are shut (return and suction.) Is there a flaw in my logic there?

Do you think my theory is correct in that it's just a leaky new multiport valve and backwash line valve?

 

[Poolbreh]

Do you think my theory is correct in that it's just a leaky new multiport valve and backwash line valve?

It very well could be, any way to confirm? Detaching waste line or checking the end of it? Cut it temporarily and add a union?
If it’s leaking your mpv is the problem. Does the pool only leak when the pump is on? If it’s not mpv you can isolate returns(return everything to spa) vice versa, monitor.