I am setting up a 30 gallon fish only tank. I bought a Marinland 200 bio-wheel filter. Should I use an undergravel filter as well with a powerhead? Is just the Bio-wheel filter enough?
Don't use the undergravel filter, it will turn into a nitrate factory. Also use sand instead of Crushed Coral. Use your filter and then add two powerheads into the tank for water circulation...
If you are determined to use the UGF, you can set up a plenum. It is just an UGF without the water flow. You just set up the filter plates and layer the substrate over it. The area of "dead water" is supposed to be beneficial.