I posted here last year with some of my pool issues, so am posting again with a follow-up and questions. Last year, I had cleaned my Hayward cartridge filter for the first time by myself. So far, so good. Turned the pump on and apparently a "clog" had developed, maybe some debris was sucked into a line. Pool guy came out and shot C02 into the skimmer and the jandy valve to clear the clog. After a couple of days, the clog finally cleared. However, at that time, I noticed the level in the pool dropping after a couple of days which was abnormal. Did bucket test. Pool okay when pump not running, but lost water when pump running.

Various pool forums and advisors had said maybe the Jandy valve was leaking and that was the cause of the lowered level. There are no visible leaks in the pool equipment above ground. I just got off the phone with a fairly well respected pool company in my area and they told me that from what I am describing, it almost has to be an underground pipe leak, and NOT a valve that is causing the pool to lose water when the pump is on. They said that if the jandy were at fault, I would be able to see the water leaking from it above ground.

I asked if there was a hole or some internal problem inside with the jandy valve that is causing this. They said NO.
They said that even if there was a hole or other problem inside the valve, it would still merely send water from the pool to the spa and around as it's designed to do.....there wouldn't be a water loss in the pool from that. I explored the valve issue a bit more, because I didn't and don't want to jump to the conclusion that it's an underground pipe for obvious reasons (big money needed to fix). Any thoughts on this? He refused to come out and look at the valve just to make sure that it wasn't at fault for the pool level going down when the pump was on. He gave me the name of a leak detection company based on the information I gave him on the phone.

I'm just wary of being pushed into a leak detection situation when it could be a simple valve issue. The pool guy kept saying, "if water is dropping in the pool, it's going somewhere....it's going into the ground at some point in the pipe system." So, any thoughts or further advice on this before I call leak detection? This is such a bummer. All I did was clean my own filter, turn on the equipment...........bam, it developed a clog.........got it unclogged when C02 was blown in........then all this developed. I'm just so bummed that a simple thing on my part apparently set off this chain reaction of problems. Any ideas? Thanks!