First details: Older style gunite base, fiberglass wall pool. Estimated: Late 70's. Hayward system- DE Filter, MP valve, etc. ONE return line at deep end, one skimmer.
When the pool is in filter mode, I'm noticing water that puddles up from a smaller hole in the dirt floor of our pool equipment house. However, when the pool is in recirculate mode, etc. there is no leak.
The lines run underground, and there doesn't seem to be an issue at the filter/mp valve area.
Any advice other than digging it up and looking? Pool season is about over and will be closing in maybe 2 week- New England is great