How much is to much light?

[hansonfam]

HI there.

We are currently setting up a 90 gallon sps tank and are getting ready to put the lights on. The tank is 24 inches deep. We were going to put 2 400 watts on. But is that to much for that tank? Or is 2 250 watts better?
Both will be 14k bulbs. But i have both kinds of ballasts so it doesn't really matter to me either way. Just don't want to cook them with light either.

Thanks
Lisa

[chrismhaase]

what about 8x54w t-5s? Less temp and same output.. 8x54=432 then you get double output, so 432 x2=864. Then 864 divided by 90= 9.6 watts per gallon. That is alot.

or

800/90= 8.9 watts per gallon.

what do you think??

[hansonfam]

I currently have 12 39 watt t5's on my 130. I want the shimmer affect:)

I know in the end they are less heat and less money but i have always wanted the water shimmer look. So as my husband is an enigneer and makes all our lights he got his hands on some ballasts for nothing so figured now was the time to do it.

Lisa

[chrismhaase]

sounds good. well good luck and show us some pictures when you get them.

[hansonfam]

I will do. Just not to sure if the 400 watts will cook the sps? Never dealt with this much light before. Would the 250 be better?

Thanks again
Lisa

[Icefire]

I would go 250

[danskim]

250w is a better choice...
I think most people agree 250w is good enough for up to 30" deep or more.

[nava405]

for a 90 gal, 250 mh is totally enough..i'll be running 2x400watt on my 120gal tank, and i have been thinking if i should just use 250watt instead..

[Shaun120]

250 Watt for all examples listed so far...IMO.

I had a 120 set up for 5 years with 250Watt DE x2 (Lost everyting during ice storm after 14days without power). Stonies on the bottom of the tank were growing at a rate fast enough for me to worry about them out growing the tank in a few years. Not a worry now.

[cervidaejager]

I run 3 250's on my 210 and I think it's plenty if that helps.

[kensilvey]

I run 6 250 hqi 14000 k over 2 180 reefs 20'' tall.

[pjf]

If you are concerned about the amount of illumination, use a dawn-to-dusk lighting scheme. Run one lamp from 0600 to 1500 and the other lamp from 0900 to 1800. Alternatively, run your actinic lamps for 10-12 hours and the MH lamps for 4-6 hours during mid-day.

The full mid-day lighting will reach the depths of your aquarium. If the mid-day lighting photo-inhibits your SPS corals at the top of your aquarium, then they can resume photosynthesis during the lesser afternoon and morning light.

Here are a couple of articles that can help address your concerns:
http://www.advancedaquarist.com/issues/july2004/feature.htm
http://www.advancedaquarist.com/2007/3/aafeature1