I know that water flow is important, so I have 4 powerheads (2 hagens, 2 power sweeps) in a 55 live rock with fish aquarium. Three had those sponge prefilters, one had a plastic grill attachment. First a small common starfish got killed in a powerhead by getting an arm stuck. Then another star got killed in the plastic grill, so I added a sponge prefilter to that one also. Then both my nudibranchs got mangled in the powerheads. Powerheads are necessary I know but this is silly, isn't it?
Details of my set-up: 55 gallon, 72 pounds lr
, 130 watts combo fluorescent lighting clownfish, large lincolnia star, 3 serpent stars, 2 shrimp, an emerald crab, hermit crabs & snails. Plan is to add a blue tang, a royal gramma and a flame angel. Remora pro skimmer, change 7 gallons of water per week. All water parametres normal. Only exception is temperature, which is too high at 83 degrees. Thanks for all suggestions.