I have a Hayward TriStar and struggle to get the lid on and off. It's 1 year old so brand new, If I just hand tighten it seems to have air bubbles, if I give it some oomph to tighten then I can't get it back off. I am buying a rubber mallet today on my way home. I tried to get it off last night and I slipped took off the tip of my pinky and most of the nail. Should have went with the Super Pump, that lid is gold standard!