I am in the process of putting together a 40 gallon breeder freshwater aquarium using Mineralized top soil and the Dry Start Method (having just enough water initially to cover the soil/substrate and only plant foreground / carpeting plants until the tank is filled in and cycled). I have decided to purchase a 36" lighting fixture from a company called Deep Blue, which has 2 T5 bulbs along with 3 - 4 blue LED lights for night lighting and I will be using one bulb at 10000K and one bulb at 6700K.
My question is whether I should purchase their T5HE (High Efficiency) 21 watt bulbs or their T5HO (High Output) 39 watt bulbs?
My thinking is that since the tank is only 16" high before I add my soil and cover substrate that the 21 watt lights (42 watts combined) should be sufficient, on the other hand am I limiting myself in the type of plants I can grow (HC and other types need higher lighting) with only 42 total watts and I should go for the 78 watts total and either raise the unit 6 - 8 inches above the aquarium and/or use fibreglass screening to subdue the HO light a bit. Also in trying to think ahead, the purchase of the T5HO fixture would also allow me to upgrade to a 65 gallon tank later without having to buy a new light. Any advice or input would be greatly appreciated.