lighting question

drxdragon · Jan 4, 2010

hi .. i was just wondering ..i recently bought a 400w mh light with ballast .. i purchased it for my 56g tank... will that be too much watts per gallon or will i be fine? or can i put a lower wattage bulb in there without any fire issues or anything? the tank dementions are 25"h x 30"w and 18" deep.. idk who the maker is of the ballast as all the lettering is rubbed off so i cant really read anything other than were it says 400w any help would be greatly appriecated thanks ahead of time.

- dragon

acanman · Jan 4, 2010

wow thats alot of lighting for a 56gallon. i have a nova extreme pro over my 55 and i thought it was too much lighting.it was 6x54 i think.

JR's Reef · Jan 4, 2010

It should be fine as long as its high off the water. No you cant put a smaller wattage bulb on a 400 watt ballast

Mr E Wrasse · Jan 4, 2010

I would say that's a little bit overkill.... a 250w would be better suited for a 56g. A 5:1 ratio is pretty solid for a reef tank, especially if you want to have stony corals. With the 400 your pushing an 8:1 ratio.

Ike · Jan 4, 2010

Watts per gallon is pretty useless when it comes to determining proper lighting. However, 400w is overkill for that size tank and a 250w MH would have allowed you to keep anything (as far as lighting goes) and saved you a bunch on electricity.

shapermike · Jan 4, 2010

400 w is way over kill for your tank. A 250 is better and you could get away with 2 250 because you can spread the light over more area. a single 400 watt is way too much contracted light .

drxdragon · Jan 4, 2010

ah i c thanks

mr_X · Jan 5, 2010

your tank is 30" wide. a single halide isn't going to hit the corners unless it's mounted pretty high off of the tank.
generally, they say 24" per halide at a reasonable height. i don't think the 400 is too much providing you mount it up off of the tank. if you used a 20k lamp as well, you would be fine with it.

Ike · Jan 5, 2010

mr_X said:
your tank is 30" wide. a single halide isn't going to hit the corners unless it's mounted pretty high off of the tank.
generally, they say 24" per halide at a reasonable height. i don't think the 400 is too much providing you mount it up off of the tank. if you used a 20k lamp as well, you would be fine with it.

That greatly depends on the reflector, there are reflectors on the market that have no problem light a 30x30 area well.

ilovereef · Jan 5, 2010

whoa, 400 watt? if you insist on using it, hang it very high up.

cloakerpoked · Jan 5, 2010

There are a lot of factors to consider. If you're set on using this lamp, then as suggested, go with a higher color temperature (20k) and mount it higher. Of course, the higher you mount it, the more you'll probably light your floor as well, so it depends on if you really want that or not.

Electricity usage is an issue, as you'll use less with 1 250 than a 400. In a standard reflector, you'll have less light at the edges of your tank, but who wants SPS growing on their side glass anyway? That's the way I figure it anyway. You'll easily get away with 1x250w if you're smart about where you place it. 18" deep will allow you to keep SPS on the bottom with no problem, even with a 250w lamp.

I run a 250w lamp over my 60 cube (2x2x2) and am very happy with the results so far. When I had a 120 (4x2x2) I used 2x250w lamps.

Watts per gallon is only so helpful. You could put 20 65w PC lights over your 200 gallon tank, and say its enough light to grow anything anywhere, but the reality is, you'll have a lot of difficulty with it. It's all about PAR values and flow...especially when you're talking about SPS. I guess my first question to you would be what exactly are you planning to do with this tank? (all SPS, mixed, mostly acan/chalice/LPS, etc.)