[jamesdawson]

I'm also planning an 8'x4'x25" tank and have done alot of research.

The most cost effective (in terms of energy efficiency, if not initial purchase cost) lighting by far is 175W Iwasaki 15k mogul bulbs on e-ballasts and in LumenArc 3 or similar large-spread reflectors. The Iwasaki/E-ballast combo had the highest efficiency rating of any bulb tested by Sanjay Joshi. You can easily grow SPS at the sandbed under the combo i suggest.

16 x 54 watt T5 equals 864 watts versus 3 175 w setups at a total of 525 watts (should be more then enough) or 4 setups at 700 watts if you want to strongly light the ends. Bulb changeouts will also be substantially less since 16 T5 bulbs aint cheap.

To make it perfect, you would probably want to have some supplemental actinic lighting since the Iwasaki has lots of 450nm blue but almost no 420 actinic spectrum. Either VHO or T5 supplemental will take care of that one deficiency and fill in the front and back of the tank.

I have had a 48", 8 bulb Teklight and they are a pretty crappy product from a crappy company. T-5s have to be actively cooled to have maximum PAR and lifespan and the Teklight doesn't do it. If your reflector gets splashed it will permanently stain/discolor and if you put a shield on you will further cook your bulbs and deplete Par and lifespan. If you want T-5, a retro is a cheaper and better option since you can blow a fan across it.

James