MH and atinics

[fraggin]

with a 10k-15k Mh do i even need atinic lights?
was looking at getting a 10k hamilton but saw someone suggested the iwasaki brand ,not sure on which is better

also whats the best spectrum for corraline?

old tank had a 5500k on it but i think the original bulb was 6500k
and had alot of growth.

also noticed on a lot of reefs on here that the rock seems really barren, ie. no algae that i can see on the tanks with the really blue spectrum, do i need a higher k bulb to prevent HA?

 

[Hurt]

With 10K's I'd use actinics(and that is exactly what I run), with the 15K's they aren't necessary. As far as the best spectrum, coraline seems to do better under blue light(~20K, ~400nm-480nm). MH in my experience is not the best for promoting coraline algae. Generally MH puts out too much PAR; for coraline usually does better under moderate lighting.