Low water levels

[Jay]

The water level on my pool is dropping approx. half inch a day and it seems I have to fill it up every 3 days or so. I noticed when I put my heater on that there was quite a bit of water leaking under it so I figured the heater was leaking, so I turned it off, well 3 days later I found myself filling it up again. When the water was low I noticed small air bubbles coming up from the 3 main drains on the bottom of the pool. Once I filled the pool up though it stopped.Then 2 days later I'm topping it up again,do you have any advice or maybe a solution for it is driving me nuts.

Thank You in advance, Jay [/quote]