Cant figure out this pool leak

[Donny23]

We opened our 30k gallon l shaped inground pool 2 days ago. The pool is about 12 years old and we bought the house about 6 months ago and are new to owning a pool. We had the pool opened last season and it ran well with no noticeable problems.

We had the pool professionally closed last season and then opened three days ago. When the pool was opened the water level was 3/4 of the way to the top of the skimmers, so a pretty full pool. During the opening the filtration system was turned on and everything appeared to be working. After about an hour and a half the pool openers left and it appeared we would be swimming shortly.

Later that same day we noticed that water was slowly but steadily (and still is) running out of the conduit for the ground wire return which is located by the pool equipment area, about 15 feet back from the pool. The next morning we could visibly notice that the pool level had dropped between a 1/2 inch to an inch over night.

Here are some symptoms or observations I have made so far:

1) The pool did not leak during the winter season but only after we opened it and ran the pump, etc.
2) The pool has lost between 1/2 to an inch in each of the three days since we have opened it.
3) We now notice that the liner in certain areas above the water level appears puffy or pulling away from the wall a bit. Not the case last season.
4) We ran the bucket test to eliminate evaporation and try to isolate the issue. The pool does leak both with and without the pump running. It does appear, however, that we may be losing less with it off than with it on.
5) Our pool lights have not worked for some time and it is possible that water may have broken the seal or light niche.
6) After I shut off the pump the next morning i noticed a lot of bubbles. Not sure if this is from the water being low (only a few inches from the bottom of the skimmer now) or if this means anything at all.
7) I cant detect any moister at or around the pool or dampness anywhere. The only signs are the water leaking from the conduit and the pool water lowering.
Lastly, I have an installed booster pump that appears to be working and not causing any of the issues.

In summary, I'm trying to pin point my issue and am having trouble. I have nothing but questions.

What could be causing the water to pour from the ground wire conduit back by the pool equipment area?
If it was a leaking light niche then wouldn't this have been a problem during the winter as well?
Is it plumbing...a pressure side or suction side leak?
Could it be the liner? Again, why wouldn't this have been an issue prior to the opening?
Where should I cost effectively start to rule out cheaper items before targeting more expensive repairs?

Thanks in advance

[CGPoolman]

Inground leaks are always tricky. Here's a couple of things you can do for little cost.

If you can pull the light fixture from the wall, you can putty up the back of the niche where the light wire goes through. You want to put enough putty in the hole to seal it off, but not too much that you won't be able to pull the wire out should you ever have to replace the light. A bar of A-B putty is usually pretty inexpensive and you can get it at just about any hardware/home improvement store.

You can also try a "dye test" around the fittings of the pool. Most pool shops sell a syringe full of dye, or if you have a syringe at home you can use food coloring to do the same thing. Drop a little dye in the water around the skimmer plate and return fittings. If there is a leak present you should see the dye disappear into it. In a vinyl liner pool its not all that uncommon to have a leak at one of the fittings. A simple gasket replacement should fix you right up if that is the issue.

Other than that, water will sink to its own level. Mark your current water level with a piece of tape. Shut the pool off for a few days and see where the water level drops to. Wherever the water stops should give you an good idea of where the leak is. If the leak stops at a level where there are no fittings (skimmer/return/light) then most likely there is a puncture in the liner somewhere.

-CG