Lighting question for a 75G tank.

[crazyman]

My 75G All-Glass will have diy lighting. First of all, I decided on MH/PC set-up. Thing is though, I dont know whether I should go with two 175 MH with actinics OR one 175 with 50/50 PC lighting. I'm going nuts over this. I'm not too worried about cost because as far as I can tell PC isnt that much cheaper than MH lighting. I'm mostly worried about having too much lighting. I dont want to burn any corals I get. I mostly decided on a dual 175W MH setup with actinics. What i'm curious about is, how hard will it be to keep corals that dont have very big lighting needs. I should add that I will be keeping a few clams too.

Also, My initial idea was to have one 250W MH in the center and have the corals that need intense lighting be situated under the light and less light demanding corals off to the sides with PC's over them. But then I found out about a person who had one MH in the center and they didnt like the spot light effect it did in the center of the aquarium.

Anyhow, as you can see I'm confused /ubbthreads/images/graemlins/smile.gif

[tendar]

Well First off I would suggest 250 halides since your planing on some clams. 175's will work but 250's will work much better. MOst all corals will be happier under 250's than 175 also and no it is not to much light. YOu can always place lower light stuff like muchrooms on the bottom and ends but almost everything else will like the brighter light.
As towards actinic or 50/50 that would depend on the spectume of halides you plan to use. If your going to be using 65k or 10k halides then us actinic for the pc. If higher spectrum like 15k or 20k then I would go with 50/50.
The other problem with having a single halide over the middle is that AG tanks have a plastic center bace that would give over time from a halide directly over it plus it would block some of best light coming out also.

[crazyman]

What is the cost difference of running two 250's 10k bulbs compared to two 175's 10k bulbs? Initial cost I'm not too worried about, but I dont want to pay 100 dollars per month to run my aquarium in electric bills.

If 175 10k bulbs will do just fine for corals, I will go that route and once I get my clams maybe compensate with a full spectrum pc?

I'll search the net for some price comparisons between the two wattages for the electric bill cost.

[crazyman]

a rough calculation would be wattage of bulb * hours per day / 1000 right. Thats what I did and I have a fairly good idea. I'm thinking that I would rather stick with dual 175 10k's and if I choose to go with clams then raise them up a few inches.

[tendar]

That will work.