Personally for the size of tank it sounds like you have enough light. I like the combo of MH and PC. Some people swear one way and some swear the other. The MH emitts a lot of heat just so you are aware, venting will be important. I can't recall the mounting height of MH but something to be aware of the the acrylic can warp with heat. Is the acrylic attached to the lighting canopy? or is it on top of the tank? If its part of the canopy, I'm sure is heat resistant.
I read a home page where a fellow custom built an acrylic tank and had MHs above it. Well one of the cross braces cracked one day since the temp of the water verses the heat from the lamps cause too much stress on the plastic. The tank bowed and it just got worse from there.
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-Wilty
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