Pool mysteriously leaking! and discovery of cracks under liner/walls that feel to have some corrosion/scaling starting.


Jun 4, 2014
I opened the pool a couple weeks ago, Didn't run the pump and drained about nine inches of water down so it was at correct level. I went out of town for 5 days, when i got home the pool was nearly a foot lower. it took about two weeks but i got a pool service out to do leak detection (its a steel walled vynl lined pool with vermiculite ? bottom).

They found a quarter sized hole on the bottom in about 6 feet of water, a dime sized on the side two more pin pricks in the ten foot area and several cracks in the fiber glass stairs. the stairs were on the first to going into the pool, and ranged from an inch long (narrow) to about a foot and a half long.

they only patched the dime sized on the wall because the water temp was still very cold (im in wisconsin).

after they patched the wall hole i ordered some Mr. Sticky to repair the stair cracks, while waiting i got the pump and filter running, it sat for a week and ran the pump for three days straight, then we randomly lost 4-6 inches of water over nigh!!!!

I then drained the pool down past the stairs that were cracked until last night when the stair crack repairs had time to dry/harden . Also last night I put on the dive gear and patched two of the three holes on the bottom (i couldn't find the second hole they called a pin prick before dark.)

the pool level currently sits just below the skimmer level, if she hasn't gone down when i get home i plan on filling to operating level and running the plumbing again. i figured if it looses water over today i know the major leak is below the current water level. Then again last time it randomly lost a lot of water after holding water for over a week!

I did do a 30 PSI pressure test on the pool lines/filter and all i found was a tiny leak in the o ring between the pump motor and hosing. repaired that and all seems to be fine on the plumbing end!

any ideas on what could be causing this (we have had record amounts of rain this spring). hopefully the current repairs solve it but i cannot believe those small cracks and holes equated that much water loss.

Also I discovered that my walls seem to be developing scale/runt as they feel bumpy/rough in some areas! (5 years ago I wire wheeled and rustoleum painted the walls with a rust proofing paint then had a liner installed! One other discovery while diving to patch the deep end is i have found some large and small cracks/divets and areas that feel like chunks of gravel are starting to poke through the liner which look like i could be patching holes again soon.

any thoughts on how to correctly approach these two other issues? I was thinking as soon as i start springing leaks frequently to pull the liner, wire wheel/grind walls then either do the paint on cold galvanizing or some sort of epoxy then the wall foam and possibly a new pool floor?

I have some underwater pictures of the floor condition and hole size (not the cracks in stairs though) that i can post later.

Thanks guys!!!!!


TFP Expert
Bronze Supporter
In The Industry
Aug 10, 2017
Morris Cnty NJ
The stairs are gonna have to be dealt with properly, patches are just that. At some point soon you have to determine if there are voids and fill them and re-glass the stairs. If there are voids that hold water they freeze every winter and heave.

If you had rust b4 ita time for wall foam. Sand and paint deals with the face but its also behind the wall you cant see. You can also sheet the walls and pop rivet when it weakens or gets real bad. The floor should stay smooth unless you have groundwater and movement down below. Or if the pool leaked alot and caused some erosion. Get it to hold for now and plan for a repair and liner swap
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