I have a 40ft free-form IG with lots of trees around it. 1st tried the Hayward Navigator, it would get hung up on anything larger than a dime and both the steps and ladders. Last year I tried the Dolphin and it worked great. I have a mesh safety cover so I have a wonderful layer of "silt" on the bottom every year which took a week or so of vac'ing to waste and re-filling, but the Dolphin had it done in 3 8-hour cycles without any loss of water.