I got called to a 50 year old concrete pool with a 2" per day water loss. The skimmer throat was leaking and also there was a good leak around the pipe in the main drain. Both of these were sealed and there have been no other openings found in the shell. The plumbing is also fine.There is no actual sump or main drain device per se. It appears that there is just an open, unpainted, concrete sump with a pipe in it. There was a good strong water flow around the perimeter of the pipe which I sealed. The light niche is virtually non-existent as it has disintegrated over time. The light niche was embedded in concrete which has now become the niche. The wire for the light just comes in through the concrete with no conduit of any kind.

Has anyone ever found that bare concrete such as this could be porous allowing for water loss of several hundred gallons per day??? Dye testing shows nothing.
Any type of sealant that could be applied underwater??

Thanks guys.

yer i had it on a new pool which was out of the ground passive leaks had to be membraned very expensive process fully tiled glass, is there any sub soil drainage around the pool or is it free draining soil, as that amount should show up, theres nothing to me knowledge that can be applied under water to seal the whole pool, drain and epoxy membrane the pool or time for a new pool 50 years is a good innings

hope that helps :S

There is no noticeable water around the pool area. The drain is 8 ft down while the light is close to 3 ft. The rest of the pool is painted and not leaking as far as I can tell. The drain and niche are the only uncoated areas but show no flow as far as dye testing is concerned. The soil is most likely typical New England gravel which passed water rather freely.
Thanks for your response.