Good to see someone doing research before purchase.
So 440 watts PC with a tank of 75 gallons should give you 5.8 watts per gallon, which might sound fine, and perhaps you can succed with that.
I would like to point out that LTA's are going to be at the bottom of the tank, so that 5.8 gets weeker down there towards the bottom. I'm not sure about PC lighting but I know that VHO tends to lose its intensity at about 12 inches getting much weeker at 18 inches and then you should switch to halides.
5.8 watts per gallon isn't bad to start with but after 6 months,you will also be planning on getting them replaced in a couple of months.
Guess I'd tell you if it is a choice bettween getting the 440 watts and having a MH/VHO or MH/PC combo then hands down I'd do either of the combos, then there would be no doubt about enough light as those MH would have the par needed to reach the depths of a 75, 80, 90 or larger tank.
Thomas
