Hello, Everyone! I'm starting a 20 gallon long aquarium (dimensions 30"x12"x12") and will be using T5 with supplemental LED (most likely Orphek OR3) for lighting. Most T5 fixtures are either 2', 3', or 4'. Would it be better to go the smaller or 2' fixture and raise/lower as needed or a larger T5 fixture? I will be looking to grow LPS and/or softies (NO SPS IN THIS TANK).