So I'm going to be setting up my first reef tank, first salt tank in many years. I'm going with canister filters (I know what people think about them). It is a 40 breeder. I bought 2 Penn plax 700's with the idea that intake/return one each side of the tank would be beneficial. While I'm still debating this, as one larger would give the same flow with a smaller footprint in the stand, I'm starting to think of what to go in them. In freshwater I always did floss/sponge, lava rock, plastic scrubbers. I have seen people putting live rock rubble, cheato, etc., And was thinking sponge/floss and ceramic rings. What do you think would be best to go in it, and what are opinions on the two smaller vs one larger (each would give about. 4.5x gph turnover, together at 9.25x)?