which light better?

[leesanhua]

this is for 90 gallon tank.
for hard and soft coral.

2X150w 20000K (mh)

or

2X150w 10000K (mh)
2X 96w actinic (pc)

which one is better? and why?

[AZDesertRat]

You will get much better coral growth with the 10k bulbs. Although I have a 96w PC powerquad over my 15G and used 3x65w over my 20 high I prefer the look of URI VHO Super Actinics for supplementation. Much better coloration and less heat. I can wrap my hand around my 2x140w VHOs without it being hot and can't even get close to the PCs.

[szwab]

I'd go with the 10k's as you lose par with the 20k's.

when you say hard corals do you mean LPS? or SPS?

for SPS that may not be enough light depending on the placement of the corals in the tank. IMO

[leesanhua]

mostly lps. but might have 1 or 2 sps. is it ok?

[jimbo045]

I would go with the 10,000Ks. JD

[mg426]

10 ks get my vote

[szwab]

<a href=showthread.php?s=&postid=7313102#post7313102 target=_blank>Originally posted</a> by leesanhua
mostly lps. but might have 1 or 2 sps. is it ok?

just place them in the top 1/3 of the tank

[Ludwigia73]

The 10k's will give better growth, the 20k's will give better color, not to mention be cheaper in electricity. 20k's give off a tad less heat, also, although still run hot. You won't need actinics with 20k, unless simulating sunrise sunset.

[leesanhua]

thanks. i know which i want to choose

[AZDesertRat]

20k bulbs draw 250 watts just like 10k bulbs draw 250 watts. Any power difference would be dependent on the bulb/ballast combination. 20k will be real real blue and corals will not glow like with the 10k VHO actinic combo. If you don't want to supplement go with a 14-15k range bulb, better coral growth and better color than 20k but not as good as 10k/VHO combo.

[robsmith32]

um, I think he was referring to the total watts is less at 20k as the light isn't as intense and doesn't heat up the water or house as much therefore not requiring as much wattage to cool it.

i'd use 10k if was xm or hamilton with actinics, or just use 150w iwasaki aqua2 20k. jUst put some in yesterday. Much brighter then the 14k that was in it. Looks the same in color as my t5 that is a single 10k and a single 03 actinic. Granted MUCH brighter and has the shimmer of halide.
the t5 is a normal, not the ho, so not really fair on the brightness scale.
Most would want a darker shade of blue, but if you've seen xm 10k and hamilton 14k, the aqua 2 i'd say is close to the light blue you see on the 2 sided aquarium backgrounds where the light blue is solid, at least to my cone challenged eyes..