Normal Water Loss for Closed Pool

[HobbitPool]

I closed my above ground pool 14 days ago., and have lost 0.28" of water per day in a 24' diameter circular pool, or about 79 gallons per day. Is this normal?

I would typically roughly that same amount or a little more without the winter cover on it. Pool skimmer/intake has the cover over it and a plug on the bottom, and the return is capped off. The pool has a solid winter cover on it with clips and normal ratchet strap. Here is the historical weather for that period, Buffalo, NY Weather History | Weather Underground.

 

[ajw22]

Properly closed and covered the pool should be a sealed balloon with no water loss.

 

[Mdragger88]

Are you using a cover pump? If so you may be pulling water through the cover.
Otherwise I would say you have a leak somewhere, either through one of your plugs or the liner itself.

 

[HobbitPool]

Are you using a cover pump? If so you may be pulling water through the cover.
Otherwise I would say you have a leak somewhere, either through one of your plugs or the liner itself.

Thanks for your reply. Yes, I'm using an automatic cover pump, Wayne WPCP250 (WAYNE WPCP250 Pool Cover Pump | WAYNE Pumps). The solid cover is brand new, one of the thicker variations, and has no holes. I don't think the cover pump would pull water through the cover in this case. Water level is below inlet/outlet ports by several inches, so no leaks going through plugs. Seems most likely it is a vinyl liner leak. Given that this is the time of year with heavy leaves falling and colder temperatures, I will likely wait to find the leak when opening next year.

What would be a safe minimum level to let the pool drain to, before refilling it with a hose? I can keep filling it periodically until opening, though unfortunately it will deplete my chemistry.

 

[Newdude]

Seems most likely it is a vinyl liner leak.

Pun intended ?

Remove the pump and compare to what you've seen. Report back.

 

[HobbitPool]

Pun intended ?

Remove the pump and compare to what you've seen. Report back.

pun not intended, though I now see it. There's been almost no rain over the last two weeks, thus no water on the cover, and consequently the automatic pump has been off. Nonetheless, I unplugged it, and will monitor the water level over the next few days.

 

[Mdragger88]

Mine has done it through my brand new “15 year” cover. I kept seeing the same very small puddle and thinking it wasn’t doing anything but it was infact pumping periodically.
I now sit it on top of an upside down frisbee to prevent it from occurring and remove it from the cover when there’s periods of no rain.

As for the water level in the pool -
If the pool is buried at all you don’t want the water level to fall below the surrounding earth or you risk a cave in.

If not buried, & uncovered, no lower than 18 inches remaining or you risk the liner shifting. The water provides support/stability for the walls so this condition shouldn’t remain for an extended time without bracing the walls.
** If its covered, the cover should always be supported by the water inside the pool or precipitation will weigh down the cover and pull the walls/top rails in.

 

[HobbitPool]

Thanks everyone for your feedback. After removing the pump, I was still losing roughly the same amount of water. Consequently, I had a pool leak contractor (not associated with a pool store) come over and they found 5 different leaks. Waterline is now holding normally.

 

[dereksanders]

Where were the leaks? Curiosity is killing me.

 

[HobbitPool]

Where were the leaks? Curiosity is killing me.

I understand. 4 of 5 holes where on the bottom of the pool right near the side wall, also close to a vinyl seam, near the skimmer, and where a vertical section of two external walls join together. The last hole was on the opposite side of the pool, on the bottom, about 4 inches from the wall.