I get where you are going. Wouldnt it be more like [<5>prime<4>prime<5>]= 24?I would put one at 8” and one at 16”
|<-8”->prime<-8”->prime<-8”->|
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Would that give enough distance from the sides without a lot of light spill? I am not a prime user or really know very much at all on them. I have heard they are pretty good nano lights, we sold a ton of them at the lfs for smaller tanks. I dont really have much hands on with them though.