The Mag7 pump that came with my 55g cube/15g sump was running intermittently so I decided to get Jebao based on recommendation. I got DCP-6500 (1710gph) which was an overkill and was causing this flushing effect in the overflow. So I switched it with DCP-3500(925gph), even this one is doing the same unless I have the power down to 30% and the return valve half ways shut. Is Jebao just not compatible with my sump? Should I go for smaller pump? I got replacement parts for Mag7, it is noisy.