beccarue

I hope you guys can help! I have been in a battle with this issue for a few months now. But I am not convinced that there is an underground leak, but it hasn't been tested for either. So I run the pump with the spa (in) and the pool (out). Water goes from the pool, to the filter, back to the spa. The spa is raised and flows I to the pool. The water level will be normal and within 4 hours, the pool water level is down to the skimmer wall. Some things we recently checked and replaced are : a spring loaded check valve, and 2 jandy valves. The filter is a hayward 4-cartridge filter. There is also the in ground cleaning things that seem to work fine when the valves are on pool and pool. There is no visible water anyway around that would indicate this much of a leak and all the brick work around is solid. Does anybody have any a possible suggestions? I'm not sure how to post pics but I will figure it out if it helps.