About to switch to MH from T5HO, need advice please :)

Right now I have a 6x54 watt t5HO fixture over a regular 90 gallon tank. Induvidual reflectors.

I'm about to downgrade tanks to a 75 gallon (same footprint as the 90, only shorter) and I was going to buy this system:

Hamilton HQI Reefstar Lighting System

I'm getting a great deal on 2, with 14K bulbs.

I want to be able to keep sps on top, and some shrooms and things on the bottom. My rockwork will be stacked about 1/2 way up the 75, to give the sps room to grow.

My questions are:

1)How high off the tank should I place these fixtures in order to keep sps on top of the rocks, and shrooms on the sandbed?

2) will this excess heat run my tank hotter than 82 during the day? I plan to add fans, but no chiller?

3) I want fast(est) growth, should I replace the 14K with 10K bulbs and supplement actinics w/2 or 4 t5HO bulbs?

4) also tied to question # 3. I LOVE the look of 20K radium bulbs, will I have exceptional growth/color with this bulb? or should I just stick with closer to daylight spectrum (ie 10K with actinics supplementation)? Growth is more important to me than color right now (i'll be starting with a bunch of little frags in the 75). Maybe down the road I can gradually add a diferent spectrum for "coloring up" the colonies once they grow?


5) if I add t5 actinic supplementation, what will the lighting schedule look like on the tank? what kind of a photo period should I have?

6) should I just stick with 14K bulbs with no actinics on the side?


Thanks for helping guys

 

Glad I could help. If you have anymore questions, just ask.

 

Thank You very much!

Also you suggested that 2x250 watt mh would be too much, should I go with 2x150 watt mh? I Feel like I have to get 2, I have a center brace in the middle, unless I put 1 250 watt 12" directly above the center brace, but would'nt that cause a large "shaded" (less par, but i'm sure things will still grow...) area directly in the center of the tank?

Also, what do you think about DE vs. SE? Except for a few select bulbs that dont come in one type or the other, is there a definite difference in performance?