Leak in the main drain return

[nathanj]

Pool has had a slow leak the past several seasons, unable to be found by local pool repair folks. Over the winter, water level was lowered to below the jets and skimmers, all water blown out of pipes, and plugs applied. Water level remained constant. Upon opening the pool, water leak from previous seasons still present, but much worse. 1.5 to 1.75 inches lost per 24 hours. Allowed the water level to get below the jets and skimmers, and water level continues at same rate, even with the pump off. As I type this, water level keeps dropping.
My thought at this point is to completely drain the pool and see if we can determine if the leak is near one of the 2 main drains in the pool bottom vs somewhere deep under the gunite bottom. If the leak can't be found without digging up the whole thing, is just plugging up the 2 main drains a good idea? These 2 drains are about 3-4 feet apart, and they join together before returning to the pump. As far as water return, there is a 1 deep and 1 shallow skimmer, as well as a vacuum line that is near the middle of the pool on the wall. Would that provide enough water flow?
Any help and guidance would be appreciated. Thanks.

[ChuckGeo]

My suspicion would be in one of the main drain sumps or a leaking hydrostatic relief valve. The usual way to determine this is to put a diver in the pool to dye test the suspected areas. The main drain line is a possibility, though small, in my experience. To determine if it's leaking in the main drain pipe, run the pool on main drain only for 24 hours and measure how much the water level drops, then turn the pump off for 24 hours and measure the loss. If the measurements are the same the leak is not in the plumbing, if the "on" measurement is less than the "off" measurement suspect the main drain lne.

[GeorgeFrank]

Leak in the main pool that the repair can't be trusted to keep going that long, there's no reason for sitting that hole. You should get ready for the one weeks it breaks another period and unbiased put a get to board over the opening so you can backpedal over and over to settle it

[MYazzie]

Haven't you tried contacting the experienced plumber for it. Last week, my aunt has also complained about the leak in the main drain and was facing some pool wire damage too. She has hired Electricians Bala Cynwyd PA team who provides the pool repair service along with the electrical damage repair services. The team also gives the hot tub and sauna wiring installation and repair service. You should definitely try this one and the result is always expected to be positive if handles by the experienced team. Or else you can contact the other professional too who can help you in covering the main drain of pool.