Large water loss in short amount of time

[harryc1]

Hi all! I had something seemingly bizzare happen last evening, and wanted to see if folks have any advice. I cleaned and reinstalled my filter cartridge (as I have done periodically in the past), and then turned the pump back on. About 10-15 minutes later noticed that the pool level had dropped about 5 inches. I have a 16'x32' pool, so I imagine this was hundreds of gallons of water that left the pool and went somewhere. There is no visible surface water or wet soil anywhere around the pool, and no visible leak at the pump and filter.

I immediately removed and re-inserted the filter cartidge, sealed the filter, and ran the pump for another hour, during which time the water level fell about one more centimeter. I turned the pump off at that point (it's been off ever since), and called it a day. Waking up this morning, the water level had dopped another 3/4 inch, and now sits just below the skimmer intake level (picture attached). However, there has been no perveivable further water loss all day today (I marked the water level at the pool and inside the skimmer well with tape this morning).

I've kept the pump off since last night, and have been trying to narrow down what caused this. I don't see any obvious water movement such as water entering back through the return jets. At this point, the only possibilities that come to my mind are (1) A leak on the suction side, but my skimmer still has water inside it and it's water level has not moved down all day today, and a leak should not have caused 5 inches of water loss in 10-15 mins, or (2) something else in my system which caused the water to exit my home and into the main sewer when I ran the pump (still doesn't explain the overnight water loss after pump was off).

I bought the home about a year ago, and am attaching a few pictures of my pool setup, to see if folks think there is something that I may be unaware of in my pool setup which could be at play here. Thanks in advance!

 

[JJ_Tex]

I would start with the filter since you just messed with it. Is it leaking or is there water coming out by the pad when running?

 

[Jimrahbe]

Harry,

Show us a pic of the other side the filter..

I know you said you cleaned the cartridge, but I want to make sure that you don't have any backwash valve on the other side..

Sounds to me like the leak is bad when the pump is running and not as bad when the pump is off..

Hard to tell in your pic, but it appears that there is one input to the pump and only one input from the filter and back to the pool (Assumes the solar is off like in the pic)

Unfortunately, if this is true, then it sound like the leak is in an underground return line.

Thanks,

Jim R.

 

[harryc1]

Thanks a lot JJ & Jim. No leak or water coming out the equipment pad. Jim, you're correct that there is only one input to the pump and one input from the filter that goes back to the pool (solar is closed & capped off at the roof). I attached a couple more pics of the pump and filter from different angles.

As of writing this Tuesday evening, the water level has kept dropping about an inch every 24 hours since Saturday (pump has been off since Saturday). The water level fell below both the skimmer and the mystery hole by the pool ladder yesterday. I also capped off said mystery hole and the two return jets last night, but the water loss has continued into today. I also did a bucket test last night, and the bucket lost literally no water overnight while the pool lost about half an inch in that time, so it's definitely a leak somewhere.

At this point the only things remaining below the water level are the two capped return jets, a pool light and liner. I'll be doing a food color test on the light tomorrow (tried doing one briefly today but it's raining and windy today, so it was hard to make sense of anything).

 

[harryc1]

Wednesday morning update: Did a food coloring test on the two return jets & the pool light, no leaks visible

 

[harryc1]

Ended up being a rip in the liner at the base of the pool. Had stupidly used a long 2x4 to dislodge some debris gathered in the deep part of the pool a couple days before the sudden noticable water loss started, and that must have damaged the liner. Patched the rip but still losing a few mm of water every 24 hours so now doing the bucket test again to see if that's evaporation, or if there are more, smaller & tough to see tears in the liner.