3 watts per gallon on a heater is the general minimum. It also depends on how warm/cold you keep your house. I like to use 5 watts per gallon when I can. For 30 gallon tank works out to 1000-150W. I prefer the higher number.
For filtering, my "magic" or preferred turn-over rate is 6X per hour minimum. For messy fish I try for 8-10X per hour. It also depends if fish can handle the stronger current generated and if the tank is planted or not. For sumps or canister I look for about 3X an hour.