Most times its not them being stuck on the suction of the filters that is killing them, it is something else and they just end up there. Test all your water parameters first and make sure all is ok. Other than that, it sounds like you do not have an overflow. You may want to consider using an overflow box to pull water from the tank and then filter. Is this a saltwater tank, usually don't see those types of filters on them. What are your tank specs and what's the equipment you are running? Reef tank, fish only or fowlr?