Oh wow, never thought of cycling the tank without a few fish. Makes alot of sense though. If I let the tank finish the biological cycle then drain it it may be ok hopefully. The emperor 400 has two bio wheels and two fillable cartridges behind each filter pad. I filled both of those cartridges with bio media instead of carbon. But to be honest now that I look at my tank the gravel is only about 2" deep, thinking I need atleast another inch. Flourite on top no good? Also, still wondering if that led light I mentioned will be good. Thanks. Loving this forum, so much good info to read up on.