are you asking which bulb you will get better color with? if you want color go with 20k but for growth go with 10k. i am using 14k althoguh 13.5k is sposed to be good too i choose to go in the middle get color and growth at the same time. but anyway to answer your queston go with 20k for color, although you will not be able to keep yellows under 20k you really need 10k to kepp yellow.
i got 4 mh 1-2-3-4 all the way a long the tank
1=400 10k ushio
2=400 20k coralvue
3=400 20k coralvue
4=400 10k ushio
2-20k is inside ,,2-10k both out side for 2 weeks now,,i start to like the color change ,,will see again in the next 2 week?????,,already 've seen what is look like 4 -10k across.,
yes, i agree not by the book
The blue side of the spectrum (20K) will penetrate deeper into the water which I believe would be the explanation for the excellent colors. I am still up in the air about what to use on my 360. I like the look of my 250w Coralvue 10k that is supplimented by 2 65w PC actinics on my little tank. But I might try going to other way around using 400W 20K or 14K's supplimented by VHO Aquasun bulbs for the big tank. Personally the 20K's alone just appear to blue for my tastes.....