We recently purchased our home that has an in ground pool. Fortunately we know the previous-previous owner, so he has been helpful with what and when was done to the pool up until he sold the home 5 years ago. Roughly 6 years ago the pool's deep end was filled in to a depth of 4' and the entire pool was redone at this point in time. We opened the pool last weekend and are losing roughly 4" of water every 16 hours the pump is running. I originally thought it was the two skimmers so I plugged them back off and bypassed them at the pump. (This resulted in no change). I have left them bypassed and was running only the drain in the deep end. I ran the pump for 4 hours this morning and noticed a water level loss of 1-2". We Have three return jets on the south side of the pool and one on the north side in between the two skimmer baskets. I have plugged the three jets on the south side in the pool and closed them off at the pump pad. I will check in the morning and see if I'm losing water without running the pump. I did finally see all of the water that we're losing has made its way about 40 feet from the pool out in our yard where it is sloped downhill. My question is, I fear we have a leak at the main drain in the bottom, because when the pump running I'm not seeing any bubbles in the return jets, but I am seeing a small amount of air bubbles in the pump basket. how bad is it to repair and what is a ballpark cost to fix it? Are there other things I should be looking for first before we shell out some money to have some find the leak?