Suggested Lighting for 100GRR

[T8T]

Hello All: Great Site!
I am in the planning stages for a 100g RR 60x18x20 tank. I need lighting suggestions. I know I can get by fairly cheap by using a VHO Retro but I was wanting to keep some sps corals eventually. I'd rather spend the $$ in the beginning than have to revamp later.
If I went with MH... What would be better? 2x250w or 3x175w. I'd prefer that light to cast evenly through they tank. I just haven't personally seen any 100g setups to know what to go with. I would most likely supplement the VHO actinics. any advice would be appreaciated.
Thanks T8T

 

[jandree22]

5’ is a somewhat unusual length of tank… most are either 4’ or 6’. It’s hard to say because the MH rule of thumb is one bulb for every 2’ of tank. Either way, I would go with the 250w, no questions asked. There’s not enough price difference with the 175w’s to justify the step down, IMO. I would say you could get away with 2 bulbs, but understand that it will most likely cause a slightly uneven spread of light. 3 bulbs would obviously eliminate this, but might be an overkill as far as the heat and space issues.

Either way, go with at least 250W…

And BTW... :welcome:

 

[T8T]

Thanks for the welcome!

One more question... Do you think that the mounting orientation of the reflectors would make any difference? Perpendicular vs. Parallel?

 

[ChrisRD]

How many crossbraces does the tank have? Depending on that and which reflectors you choose you may be able to use 2 lamps.

250 watters are plenty for a 20" high tank - even with light demanding corals at the bottom of the tank. Lower wattage lamps can actually work fine too depending on which particular lamp+ballast+reflector combination you choose. There are some new 175 watters out now that actually provide more light than many higher wattage lamps - the Iwasaki Aqua2s. See Sanjay's article (scroll to the bottom):
http://www.advancedaquarist.com/2005/12/review

As for the reflectors - yes orientation can make a difference depending on reflector design.
Check out Sanjay's reflector articles to see how various designs perform:
http://www.reeflightinginfo.arvixe.com/articles.htm.

HTH

 

[Anonymous]

I would think that 2 250w would be enough. Seeing that the tank is 20" deep instead of 24" you could raise the lights an extra 2-3 inches to get a little more spread.

 

[Meloco14]

I agree with the above. As Chris mentioned, your bracing can effect your lighting. If you have a wide center brace, I would go with a 250 on either side of it. If it is eurobraced, you could still go with 2 250's, or 2 250's with a 175 in the middle, or 3 250's. Having 3 bulbs will ensure even light coverage, but if you play around with just 2 bulbs you should be able to get a pretty good spread. You might want to look at the lumenarc reflectors, as I've heard they have a bigger spread than other reflectors. That will help a lot if you go with only 2 bulbs. HTH