How much light?

E

eman

My tank is 78" long 30" wide and 24" high. I have an IceCap 660 that I was thinking about running 4 - 3' super actinic vho lamps. I like the look of MH so my question is how many do I need for my tank. From what I have come up with 250w lamps are fine with the 24" deep. I don't know how many I need across my tank. Will 3 - 250w 10K MH be fine across my tank or do I need 4 because of the 30" wide. I like the 250w IceCap Balast as well as the Spider Reflectors. I do not want to over due the lighting because of energy cost. I will also be mounting the lamps close to 18" above the tank because I have acrylic.

Thanks,
 
I think you would have to have at least 3 MH bulbs. I have two 250w MHs in my 140 and it is only 48" across.

If you're concerned with the energy costs, perhaps the 175w bulbs would be a better choice for you. However, if you plan on have SPS (hard) corals, 250w would be better for you.
 
I'd go 3 250W.. but you could just as easily go 2-250 or 2-400 and just put them in closer to the middle, then supplement with T-5. If you are building this from scratch, go with T-5 and forget VHO. With 2 you would have them roughly at 25" center and 55" center. If you went 3 it would be 19", 39", 59" roughly. I think it would also depend on how high up from the tank they would sit. The higher up you go, the more coverage you get but less intensity. Having lesser light zones is NOT a bad thing as it would allow you to have a 3-D adjustment in some cases for corals and the like. Not only could you adjust light intensity for them up and down, but you could do it left and right as well offering more flexibility.
 
Look into the Luminarc reflectors which will give you the best penetration and spread. Could get by with 3 MH's using these reflectors. Check out a fairly recent past post. There was one that went into detail regarding these reflectors and had a link to a report by one of the hobby's top expert on aquarium lighting
 
Thanks for all the input! I will be going with sps in the future. After reading the article about the reflectors I think that I need 3 lamps. Will the 250w lamps cover as much area as the 400w lamps in the article? I guess knowing before hand about the par loss concerning the reflectors is a good thing but the L3 reflectors cost more than double than the spider reflectors. Whats another $210?

Concerning the vho vs T5. I have the IceCap 660 ballast already and would like to reuse it. I have some T5 Helios lights but they seem cheep to me compared to the IceCap. I don't want to buy another ballast for the actinic lamps or more end caps unless it will make some huge difference like loosing 7% par or 25%. Are the Helios lights cheep? Does my math look correct on the energy savings?

4- 3' T5 = 156w * 12hrs = 1872w * 365days = 683,280w / 1kwh = 683.28kwh * $.145 = $99.07

4- 3' T12 = 380w * 12hrs = 4560w * 365days = 1664400w / 1kwh = 1664.4 * $.145 = $241.33
 
being only 24 inches tall 400 watts in my opinion would be too much, usually most hobbyists go with 400 watts when they need to penetrate when the tank depth is deeper than yours. with you adding 18" gap between bottom of reflector I would recommend L3 reflectors 250 watt bulbs. but that is up to you...l3 reflectors put the majority of the light from your mh bulbs back into your tank that is why they are highly rated.
 
You can run that Icecap with T-5... There is a post that talks about someplace.... but it will drive them. 400W is too much in my opinion, go with 250.
 
Thanks for all the input. If I go with T5's it will be to save on energy. Does anyone have any experience with Helios lights?
 
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