I was using 42w cfl's, but by the time I had 9 of them in there I was using almost as much electric as a 400hps and also as much heat. So I took them out and put the 400 hps in. Mine does not seem very noisy, but if you get a digital ballast you wont have that problem. And they (the ballast) does not heat up like the magnetic ones. And use HPS for flower not MH.