I have been looking at retro fixtures but I do not know much about ballast. What brand name should I go with and what type should I get. Does it matter or not.
I would suggest electronic ballasts. There is very little difference in performance among MH
electronic ballasts, so name brand doesn't make a whole lot of difference. What bulb you choose makes a huge difference tho. Some bulbs perform much better than others. (I'm assuming you are talking about single ended bulbs)
My existing tank is a 55 gal (48"x12"x21")and my next tank will be a 125 gal (48"x24"x24") so I am looking at dual 250W MH lights
Actually, those are the dimensions for a 120. A 125g tank is 6' long.
's will work fine for a 120. If you get top of the line Lumenarc or LumenBright reflectors (aprox $100 each), you can easily get away with 175w MH
bulbs and save some $ in electric use.