I concur with the previous posts regarding CO2. Addition of CO2 will make your plants grow a whole lot better without a major algae headache if you fertilize accordingly. Because of the size of your tank, you will need quite a bit of CO2 so do a research on some good reactors. 72" makes it a long tank so a powerhead (better yet 2) would distribute CO2 rich water throughout the tank and help to avoid areas of stagnation. You can get powerheads with strainers at the intake end so your fish doesn't get sucked in.