I'm making a hood for my 37 g tank.. was wondering how high above the water I should place the top for a MH and PC combo. It will be open back .. if that helps.
As close as you can get it without needing a chiller or risking a splash onto a bulb. Leave a little area above the bulbs for heat to go. I would probably do something like 12 or so inches high and try to lower the bulbs with brackets until I was happy how much the water was getting heated.
