Decided over the weekend to switch from fresh to salt. The tank is a 125gl. I have two penguin 350s and 2 of the marineland C360 canister filter. I bought the phosphate-zorb and Ken products nitrate lock for media inside the canisters because everything I've read on the salt is that these are the two biggest fish killers. Anyway I do not wanna do the live rock or a reef, what kind of fake rock if any can I put in there? would the fake concrete be ok? Also is it ok to run the sponge filters inside the tank? I have them hooked up to the powerheads, I plan on putting a few speices of puffer and a lion inside the tank so nothing small will be in there to eat the sponges. I filled the tank about half way with the nurti-sea live sea water and mixed the rest, how long should I wait before testing a few damsels in it? Thanks again for the help