I had a new problem when opening the pool this year. I can't find anything even similar in the forum. Everything seems to be working OK, water is clear, pump is working fine, filter pressure is the same as usual. But when I shut off the pump, all the water from the filter, pump, and hoses shoots up out of the skimmer. About 6 feet in the air plus back into the pool. Very suddenly and every time. You have enough warning from the gurgling to get out of the way. Barely.
I don't even know if the problem is with the filter, the pump, or something else. It's like there's a valve that should be preventing that, isn't working. Is there such a thing? I really need some ideas.