Ok I have had my tank set up for over a year now, and seems to be doing really well. My bf gave me a Penguin 400 from one of his tanks to put on my saltwater tank. I previously had a Penguin 170, i think. (I took the bio-wheels off). Before the filter switch, my nitrates hoovered around 0-10ppm. About 10 days after the filter switch I tested the water planning on doing a water change and the nitrates were 40+! I had forgotten to take the biowheels off the Penguin 400. Is this what caused the nitrate spike? No fish, snails, or shrimp were harmed though.
Go Big Blue!!