Thank You to all of whom have answered problems about leaks.Of course none of them match my senario so here goes...We bought a house with a 20 x 40 inground sand filtered vinyl liner pool. we live in the chicagoland area. Last year we had no major issues. This year we have been losing water-3 inches per day.Our pool company has come out and pressure tested all returns. They found a leak in the fountain which we just disconnected and plugged temporarily. We are still losing water. In an attempt to find the leak we currently have one return in the deep end on along with the main drain on the bottom. Both skimmers are off since the level has dropped below the skimmer mouths. We have 2 other returns on the stairs which both work on the same line(according to the pool man).He had turned that line off.Since i was feeling ineffective i decided to again go around the pool with food coloring to see what i could find.One of the stair return "eyeballs" (which was off )sucked in dye. I capped it and continued around the pool.The return in the deep end that was on and pushing out a jet of water concurrently sucked the dye in too! what does this mean? i thought returns only pushed out water?! My waste hose does not seem to be leaking-could that be it even though the water level is below the skimmers?i am unsure how the circulation of the pool water truly works. As a nurse it seems the human body is simpler in this case...All insight would be truly appreciated.