My Dolphin was always getting stuck on the drains, to the point where I had to constantly check on it. Many times I would take the brush and push it off one drain, and it would go directly to the other drain and get stuck again!!! It didn't matter whether the pump was running on not, it would get stuck at least 5 or 6 times per cleaning. I finally broke down and bought 2 Polaris drain covers. It hasn't gotten stuck since. A costly solution, but now I can throw it in at night and wake up to a completely cleaned pool!