New to MH and also need to build a hood

[Ananick]

I will soon be receiving my new 30g high Sea Clear tank, which measures 24" x 24" x 13". I was planning on building a hood out of wood (although not sure what kind). I was planning on initally housing 4 x 24w PC bulbs in the hood initally and then in the relatively near future adding two 70w halides to go with the PC's.

All that being said, there are some things I'd like to see if I can get clarified.

1. I was thinking of having a 10"h hood (2" would overlap the edge of the tank so it would really effectively be 8"h). Is 8" too high or too low for MH bulbs? This height should allow me to also get my arm in the tank, which is something I'll need to be able to do.

2. Given the height specifications I just mentioned, is 8" too high for PC bulbs to be effective?

I was thinking about building the hood out of 1/2" MDF or possibly something thicker. I really don't want to spend tons of money on hardwoods or anything. The hood will be painted black to match the stand so fancy wood isn't really necessary. The hood would have either two 120mm fans (4") or four 120mm fans. I don't know if only two fans moving air through the hood would be enough. The fans would be on the ends of the stand and not on the top or back.

I've read a few posts about people attaching their MH lighting directly to the wood, but I think I would follow the example of adding nylon spacers between the reflectors and the wood hood. I was thinking of placing a sheet of 1/4" clear acrylic between the top of the tank and the lights to help any moisture away from the lights. I'm not sure how heat-sensitive acrylic is (although I think 1/4" is pretty beefy) and how far it would potentially need to be away from the lights. Then again, maybe it would be better to not have any barriers between the lights and top of the hood so that proper oxygen exchange can take place and also so the warm air that's generated in the entire hood can be blown out of the tank.

Anyway, if anybody can offer tips or advice I would appreciate it.
If I think of any other questions I'll bring those up as well.