Nice setup Greg I just skimmed through this write up a couple thing to think about as I went through it when I did my build.
1) I don't think you have enough air flow to cool your entire heat-sink if you run the LED at full blast.
2) I raised my fans about 2" over the heat-sink as this will spread the air flow through the entire array and had them mounted on the top cover with full enclosure except the sides,keeping in mind I used 2 x 120w 4" fans for my array witch holds at least 60 LED (too lazy to count now
running full power 1500Ma for whites and 1000Ma for royal blue)
3) If you are gluing the LED on the heat-sink I would use Arctic silver thermal adhesive as I read it in the past to be the best product for heat transfer and use as little as possible.
Originally I had optics on all LED and yes if your setup is close to the water you will have a disco affect,I see 2 ways to have it running without the disco dancing water put optics on all white and blue LED and none on the other colors as this will give your colors a 180 degree spread.
You are more than welcome to come by and investigate my array