If you don't want to order any different LEDs, I think I might try this:

http://i1035.photobucket.com/albums/...efault-001.jpg

I swapped the positions of the centre W and RB.

EDIT: Just keep in mind that I don't know a whole lot about this. I'm just learning, too.

I'd think long and hard about this as I'm guessing you're epoxying these boards down making changing them later rather difficult. Shelly did probably as good as it gets but it's still going to be awfully color spotty. I can't imagine why anyone would recommend this quantity and ratio of LEDs, you'll end up running whites at like 30%, blue at 100%, and reds and greens at 5%. Especially with 45 degree optics on the white for a 20" tall tank, is the plan to hang the fixture really high?

For a little more you could have gone with 3 drivers powering with 8 boards of blue, 8 R-blue and 8 Neutral white and I wouldn't use optics at all. I don't think reds and greens would be much benefit if you use neutral whites but if you really wanted them after trying this combination you could easily add them with a lower powered string to prevent spots.

Here's the link to my .DXF (in case anyone wants to fiddle with it some more . . . I just got really badly slammed with work).

https://www.dropbox.com/s/c6iykgsuzlvfc45/axe_man16.dxf

It can be downloaded by clicking the "Download" icon in the top right of the screen after clicking the link.

Thanks. The layout is similar to one of the layouts I did up a week or so ago. I guess if the colors are a bit spotty I can try taking a few lenses off to help.