^ Good points.
I also don't understand why you would want a frag tank
and a growout tank. Could you explain? Are you planning on running a bit of a side business? It seems like rather an over-sized system to feed a 150-gallon reef. I would imagine you would have plenty of space using a standard 40-gallon tank or two (and much cheaper to set up).
Check into an HVR unit. They are a bit pricey to get going, but they will pay for themselves in no time with energy savings. Not mention saving your house form rotting out...
Consider adding glass tops to the tanks (keep the sump open, skimmer will provide plenty of air exchange) to help lower evaporation. If you make shallower tanks like sphelps suggests you should be able to use T5s for lighting so heat won't be so bad, and the tanks can handle having a lid.
With the amount of water you have going I would suggest you look at 55-65 gallon drums for RO and salt mixing vats. Your proposed 30-gallon vats will need constant refilling.