I have determined my in-ground plaster pool has a leak "somewhere," but I don't know where to start looking for it. Here is what I've found:
1. If I don't run the pumps (booster is currently disabled while I try to figure this out), the water level goes down about 1/8" or so per day, which matches my bucket test results. So, the pool leak is insignificant when the pumps don't run.
2. If I run the main pump for nine hours, the water level goes down about 5/8". I have all the jets turned downward to keep from perturbing the surface, in case the turbulence increased the rate of evaporation. So, it seems my leak is costing me about a 1/2" of water each day.
I cannot see any leaks in any of the visible plumbing or solar array and none of the ground is visibly wet. Most of the pipes leading to and from the pool are only about 10-15" below the surface and only those immediately around the pool (drain, returns, etc.) are any deeper than that. The equipment pad is below the pool's water line, so I'm baffled as to why it doesn't leak even with the equipment off, unless the return pressure is adequate to overcome the leak's otherwise trivial flow. I assume the leak is in the return side as it's the only part that's pressurized when the equipment runs, right?
The surface area of my pool is about 420 square feet, so the rate of loss translates to roughly 15 gallons per hour, by my rough calculations.
Has anyone used a leak detection service? What do they cost? How does it work? Is there a DIY leak detection method I should try? Is this a big enough leak to detect or even worry about?
Thanks in advance