Over a 40-breeder you can definitely use a 150w halide (if you have a 150w already). If you have a 250w or bigger, it's too much for sure.
Raise the 150w halide up about 12-15" over the water surface to start with, and definitely use DIY CO2.
Since you already have the light, you might as well give it a try.
And (speaking from opinion here) please don't buy that light in post #20. It's probably a decent light but power compacts are inefficient and costly to re-lamp. I have never liked anything made by Coralife for lights; they tend to be unreliable.... and I HATE power compacts. I would personally use a 2-bulb T5HO setup.
I briefly owned one of these that came brand new with a tank I bought from a buddy. I traded it for a water pump, but for the month I had it, I think it was a decent light for the money. Not a perfect light, but I don't have a biased grudge against Current USA like I do Coralife lol.
But really though, if you already have a 150w halide, give it a shot before you buy anything else.
And btw you can buy low-cost halide bulbs on Ebay that will work fine. They aren't the most efficient things in the world but they will do just fine for plant growth.
I would buy one labeled "10,000K" or "10K" since most of them look much more yellow than a true 10K bulb. Even good, higher priced brands like EVC 10K's are actually 6500K's according to the data I've seen.