Lighting for a 7" sps tank, 5x400w or 3x1000w?

[Pomme]

Lighting for a 7" sps tank, 5x400w or 3x1000w?

What would you suggest, i am thinking of either 5 400w low bay units:

with say 3x 20k and then two 10k bulbs.

Or have three 1000w units, with the Diamond Lumenarc 3 reflector, which did so well in Sanjays test:
http://www.advancedaquarist.com/issu...03/feature.htm



with say 3 20k bulbs. The light units will be arpund 15" from the water surface and the water depth around 20".

Andrew

[Ninong]

Andrew,

I assume you mean a 7' SPS tank and not a 7" SPS tank???

If the water depth is only 20", you should not use 1000w lamps under any circumstances. Even 400w lamps would be overkill but you could get away with it if the lights are mounted 15" above the water. You could not get away with 1000w lamps 15" above the water in a tank that shallow.

[Pomme]

yeah i meant 7 foot, its late over hear. and been working from 5 am till 10.30pm today. the great life of a diving instructor, lol.

ohhh would it cause major bleaching?

[Reefland]

The light intensity and heat would be too much. How deep is the tank going to be?

[Ninong]

yeah i meant 7 foot, its late over hear. and been working from 5 am till 10.30pm today. the great life of a diving instructor, lol.

ohhh would it cause major bleaching?

Andrew,

The light intensity in and of itself would not cause bleaching, assuming the corals were properly acclimated over a period of at least six weeks. The problem is that you can't put three 1000w metal halide lamps over a 7' tank that has only a 20" water column unless you have a gigantic chiller.

The most common use for 1000w metal halide lamps is for tanks that are a minimum of 1 m deep. The light spread from these lamps (with good reflectors) is about 1 m^2 when the lamps are mounted about 45 cm above the water. I have seen them mounted closer than that and over tanks that were not that tall but that is really overkill IMO.

[Pomme]

reefland, the tank is 2 foot high, but water depth around 20".

ninong, yeah i see your point now. Ill go for the 400s.