ok, I have two tanks with NOTHING in them...I can't have that. The two fresh tanks fish are now in the 150 and they are loving every second of it. Now I have a 55 and a 46 tall. I have taken the sand from the 150 and put it, and saltwater in the 55. I was pondering turning this tank into an aggressive tank. The thing is this, I do not want to spend tons of money on it right now as we are concentrating on filling the 175. I have a milennium 3000, a fluval and a penguin biowheel that are not being used. Heaters are here. I dont mind picking up a few smaller items for it.THere is a minimum of 6 inches of sand in the tank. What would be the best useable combination for turning this into a FO tank?