Pool is half empty overnight!

[megamomo]

Today's update:
Pool water level is now below both light fixtures. That means it is at the bottom edge of the steps and only about 6 inches remain in the shallow end. No signs that it has stopped losing water. I inspected the liner visually from the pool deck and see no signs of holes, though clearly something could be hiding at a seam, change of plane, or at the drain.

The liner is definitely fried. Again, I have no idea how old it is. I do know pH has been fine since I've lived here, which is now 10 summers, but the liner was already looking old at that point. At this point I will be getting it replaced regardless of whether that is the problem causing this leak or not.

Regarding the leaves, the pool was spotless when this process started, so the overnight where most water loss happened, there weren't many leaves at all. I does appear that the handful of leaves that were in there did get sucked into the skimmer baskets and that make have helped minimize the suction loss and allowed the pump to still maintain its prime and still suck water via the main drain even after the water level went below the skimmers.

Unfortunately that amount of leaves is a daily occurrence in the fall when it rains and is windy, which it has been doing for the last 3-4 days, though it's finally nice today. And when it frosts tonight and the leaves start falling off like rain, it will be bad again tomorrow. I will clean them out though.

I still can't believe that it's the multiport valve itself, though the pump being on driving most of the water loss means something in the system was exacerbating my water loss. The backwash hose was in the yard and even with the hard rain, I should have seen all the leaves blown away by the backwash pressure if I was really losing the water that way.

 

[PoolguyinCT]

Check your area for a pool contractor with a "leak Trac" device to scan & locate leak - or toss a volunteer fireman with a dry suit a couple benjamin$ to take a swim & find it

 

[JamesW]

I suspect that the liner has a pretty big hole. A hole in the liner can account for all of the water loss. The water loss is greatest when the pool is full and will slow down as the water level drops. I think that if you brush the leaves out if the way, the hole will be easily visible.

 

[megamomo]

I suspect that the liner has a pretty big hole. A hole in the liner can account for all of the water loss. The water loss is greatest when the pool is full and will slow down as the water level drops. I think that if you brush the leaves out if the way, the hole will be easily visible.

I am leaning toward this conclusion as well. Maybe I didn't see it before the leaves got in there b/c I simply wasn't looking for that problem. American Leak Detection won't get in an outdoor pool again until April around here. Then again, I shouldn't need them with a hole big enough to lose this much water. My local contractor was booked this week but is coming by next Monday.

So I'll circle back to one of my original questions. If this is a liner leak, do I need to patch it and fill the pool up most of the way while it sits for the winter? If the liner is being replaced in the spring, would I be risking major damage (wall collapse?) if there isn't the water weight to keep pressure on the walls?

 

[JamesW]

It might be ok, but it might not depending on the exact circumstances. You need someone on site to evaluate and advise.

 

[PoolguyinCT]

It's really impossible to tell from poolside, you can't see the condition of A frames , collar or other buried elements.. I have seen many empty panel pools winter over well, with exception of subbase & have seen many fold.
It's usually the integrity of the A framed that dictate how it will hold up.

 

[megamomo]

Pool level is below the shallow end depth now. Deep end has only about 3 feet of water remaining. I brushed the leaves away in the deep end and still see no visible hole in the liner.

The deep end has sloped walls, so there are no more 90 degree transitions between wall and floor remaining. The change of plane from the sloped walls to the floor are easily visible, so I can't imagine that I can't see a hole if one were to exist.

Sadly, I'm now much less confident in the liner being the problem. I have a bad feeling that this thing is going to empty itself completely.

If I find out that it's not the liner, I might need to start figuring out how bad this really could be and what exactly my home insurance does and does not cover. I know that the pool is considered an "other structure" in my policy, but there still may be a number of ways that the problem isn't a covered item.

 

[JamesW]

It's either the liner or main drain. You need to replace the liner anyway. If it's the main drain, you can just plug the main drain and forget it.

 

[tstex]

I agree w James - is there a way to get some dye over the main drain...if the pool continues to drain and the shallow end is empty, that tells you it's in the deeper end somewhere..that's A LOT of water seepage into the ground below pool...

 

[JamesW]

Try putting a piece of plastic over the main drain. If it's leaking, the plastic might be noticeably sucked down.

 

[megamomo]

I pushed some of the leaves around in the deep end to see if they would be sucked toward the drain when they settled. Certainly some landed at the drain, but I can't say that I saw clear evidence that they were pulled toward it.

I thought about putting some dye down there by holding a PVC pipe from the deck with the end near the drain, then pouring a small bit of dye down the pipe, but I didn't have a PVC long enough to reach. A drop of dye on the water surface dispersed randomly before sinking enough to get near the drain.

I still have seen no evidence of wetness outside the pool. Between the house and pool is a large concrete patio. We are at the very top of a pretty large hill, so I'm not surprised that the water is disappearing into the earth.

JamesW - good point on plugging the main drain. My worst fear was having to dig it up, but the two skimmers should be sufficient if necessary. Now my worst fear is something collapses over winter.

 

[borjis]

Do you have any idea what the water table is like in your area?

It does seem to be much lower than your pool if the water is leaking through the main
drain / liner area.

If it were me, I would plug the main drain and not have one when the new liner gets
installed. one less thing to worry about.

I feel lucky that my pool has no light or main drain to be possible cause for liner leak
issues.

 

[megamomo]

No, I don't know what the water table is like, but I would almost venture to say that there really isn't one to speak of. I am within a few feet of the highest point in the vicinity. The hill behind my neighbor's house drops hundreds of feet to a major river. The other directions are more gradual but still downhill. No one has sump pumps in their basements or anything like that around here.

I do like the idea of plugging the drain if it comes to that being the issue. That would be new territory for me and obviously not the normal pool setup, so I would be wondering about cleanliness. I'm guessing that could be handled in ways far cheaper than fixing the drain (getting return jets that aim downwards, maybe a robot cleaner, etc.).