I can give you some pointers here and if you want to discus more, try to come to my LED DIY party. You can bring your own stuff, you don't have to buy anything from me. It's technology hobby(LED lighting) meet so I careless what brand of products you brought to discuss with peers.
1)To lower disco effect, do not spread out the LED too much like 99% of the DIY build rampant in internet.
2)Some one in RC has devised an OK estimate by square inches of tank surface to determine how many LED you need even though I personally use another faster method. The RC method has become the norm and since it works too, so you can follow that one and there will be more peers who copied that idea without really understand what it means can still help you correctly.
3)Exercise EXTREME caution in soldering the stars and adjusting the drivers if you never seen it done before. NOT A SINGLE youtube video about DIY LED for aquarium show the danger of solder stars. Try to search OTHER electronic soldering video may provide a better understanding how to do it right.
4)Try to use common LEDs instead of blind aim for best so called efficiency. For example, given a choice of Cree XP-G vs XML, I would suggest you to go with XP-G because more as stated earlier, peers who use the the imitation strategy can still help you.
5)To increase intensity, you will need lens. This a very good strategy even though someone argued the efficiency of lens. When you use lens, you reduce a lot of power to produce the same intensity for a given area. A very useful side effect is heat generation is also lowered. Fan is one of earliest part of a DIY build to fail.
6)When using lens, a dimmer is almost A MUST because chances of coral bleaching is much higher so light acclimation and such is very important
7)A splash guard is A MUST