Is it possible I have too much light?

[rob020880]

Hello,

My tank is a 130 gal quarter cylinder and it is 30" deep. The space I have for the lighting is awkward but I have managed to squeeze in two 250 w de helios 20k bulbs running on a pfo hqi ballast and in lumenarc stealth reflectors. I also have four 24 watt T5's.

Is it possible I have too much lighting for my tank? I ask because I have several corals that do not extend their polyps and I was thinking it may be the lighting. All the water parameters are in line so I was thinking it may be the lighting.

What do you think? I was also thinking that perhaps my lighting may be too weak and I should try a 14k bulb instead of the 20ks I have now. Any suggestions?

[plateboy3293]

Mushrooms and softies need 2-3 watts per gallon if more they need to be at the bottom, lps need 4-6 watts per gallon and sps need 7-9 watts per gallon.
So sps near the top if you have 7 -9 watts per gallon followed by lps followed by softies and mushrooms

[rob020880]

So I don't have enough light for the sps since I am at around 4 watts per gallon? Would getting bulbs that have higher par help me out?

[m2434]

Unfortunately, WPG isn't a great metric. PAR is better, a 20K 250W MH will probably, have less par than a 10K, but will penetrate deeper.

One problem I see is the lgiht coverage. Flourescents are very uniform, but point-source lights, such as MHs, not so much. Even with the T-5s, the single MH isn't neccessarily illuminating all of the 130g tank well. It could very well be too much light for some corals right under it, but too little for others. Think about where the corals are in relation to the light and what they look like.

Also, for what it's worth, a 14K bulb may not actually have that different of a spectrum compared to a 20k. Much of the data I've seen suggests that typical 14 vs. 20K bulbs are more similar than different. A 10K would certainly be different, but first you need to determine if that's good or bad (or what you want)...

[rob020880]

I currently have two 250 w MH not one.

[flyyyguy]

as said...watts per gallon is a worthless measurement.

as is it hard to say from one tank to the next. What may be too much light in a low nutrient tank that isnt fed enough, might be just right or even on the weak side in a more well rounded system that could handle more feedings

with a 30" deep tank, 250's in any kelvin certainly isnt even close to too much in healthy conditions.

jmo

[m2434]

<a href=showthread.php?s=&postid=13535299#post13535299 target=_blank>Originally posted</a> by rob020880
I currently have two 250 w MH not one.

:lol: sorry, it's getting late, my eyes arn't working well :eek2: Anyway, the rest of my post it still valid, but in that case, I tend to doubt you have too little light :lol: