I'm trying to help my parents find the leak in their pool and I think I've tried everything. They lose several inches every day. Before I call a professional, I want to make sure there is nothing else that I can try. They have a 22 year old gunite pool with the original Diamond Brite finish. I've noticed the Diamond Brite is starting flake off in certain areas but I don't see any obvious cracks or a source of a leak.
I tried the food coloring/dye test. I checked all of the returns, skimmer, main drain, vacuum line, light, and even the hand rails. I didn't see any dye get sucked into any of the above. Then I capped all of the returns but the pools still lost water. My father says the pool loses more water when the pump is off but I wouldn't take his word for it.
Is there anything else that I can try?