Help with leak - suspect light niche

[Beez]

I have had a slow leak for over a year now. Have done the bucket test to verify that the pool is losing water faster than evaporation, and to verify that the loss occurs without equipment on.

The plaster is old and has several significant cracks, so that is a possibility. I have tried the food coloring test with the cracks but so far that has been inconclusive; I can't really see any food coloring entering the cracks. To me, that doesn't rule them out as a source of leak though...could easily be user error.

So as I was brushing today I noticed that the pool light doesn't fit tight against the niche. Sure enough, I can reach down and wiggle the light and it opens a crack a good .125" wide. So I followed a line straight from the light to the edge of deck and checked the soil to find that it is definitely moist, whereas the soil everywhere else around the pool deck is bone dry. Does it make sense to suspect the light niche? If so, where might it be leaking, and how would I go about diagnosing/fixing it? (BTW, I tried the food coloring test around the light housing as well with no luck. I'm either no good at executing this test, or it is unreliable. I will accept either judgement.)

Right now I'm attempting to remove the light, but the one screw I can see is being very stubborn.

TIA,
Beez

EDIT: So I removed the light but as I suspected, it didn't help because I don't know what I'm looking for!

 

[duraleigh]

That single screw connection on the light is not intended to be waterproof so that's inconclusive.

I think I would let the pool leak down until it stops and then look at that level.

 

[Beez]

That single screw connection on the light is not intended to be waterproof so that's inconclusive.

I think I would let the pool leak down until it stops and then look at that level.

Thanks, Dave! When the water cools down I will follow that advice.

But for the record, I wan't suspecting the screw but more likely the connection where the light cable goes through the niche.

 

[duraleigh]

I wan't suspecting the screw but more likely the connection where the light cable goes through the niche.

That penetration of the light cord (and the pvc pipe the power cord goes through) is not waterproof, either. The power cord is submersed until the water in the pipe reaches the same level as the top of yuour pool water.

How much is the pool losing per day (or week)?

 

[swimcmp]

Find a butyl tape product make a ball with it shove it in the conduit hole around your light cable. also look closely at the niche itself , depending on the age of it it could have deteriorated over time and could have pinholes in it.