i have about 70 times turn over flow in my 90 gallon tank, 100 gallon system, at least what i figure it to be, one closed loop whith genx 1100 gallon an hour pump going through a squid to two outputs in tank, 2 Koralia 1050's one 1400 and 1 sicce 800 on a red sea wavemaker pro and a high pressure 1100 gallon corallife pump going to the sea swirl with a 3/4 in eductor on the end. all the powerheads are no more than a year old. i have inspected some of them just because they where not working right, Koralia 1400's on a red sea wave maker. koralia sent me new parts to fix them at no charge, which is good because at the moment i am broke. they really hooked me up. but i would not say that i inspected everything for corrosion, i will tonight an see. thank you again for another lead. i do know that the metal stand that my sump is in and refuge hangs on top of is rusting in certain spots, but i am in the process of replacing it with a wood buit stand. nothing seems to ever get into the sump but i am sure i wouldn't see it if it did. you feed alot more than i do. i feed 3 days a week. tuesday is a pinch of pellet for the fish and at night when the moon lights are on i feed brightwell zooplankton soaked in coral amino. on thursday i feed the fish rods reef to the fish and corals with a cube of mysis also for fish, i again soak the coral food in coral amino, and sunday is a repeat of what i feed on thursday, i have 9 fish in the 90 with a very healthy stock of coral. i do a once a month water change at 20%.