Par38 Lighting

'm looking at the ABI 12 watt par38's for my 10g nano reef. im mostly looking to grow zoas, sofites, and lps from the euphyllia family, but i do like the idea of maybe stopping into lfs and picking up some other random lps coral every once in a while. They have one thats half white and half blue, and another thats all blue. their non controllable and non dimmable, so i was thinking of getting one of the mixed and one of the blue, to be able to control blue from white. by changing which ones i plug in. would this work, or would their being only one of each make the coverage shady? should i just go with two mixed? and what would be the best placesment if i get a white and a blue to make them seem as if their both over the center when only ones turned on, and could i turn both the whtie and blue on during day, or would the blue over power it? also would a single 24 watt one be strong enough with decent coverage? sorry for the long question but i only wanna do this once i wanna make sure i do it right