Cool, thanks agito.
I plan on making my screen tomorrow. My HPS light is permantently mounted so I can't lower it, so I'll need to find the best distance from light to put the screen and just raise my plants to it. It's a cool tube, so I was just going to keep the plants about 6-8" away from light (before I was thinking of SCROG). So if the Plants can grow an extra 12" above screen and I was going to keep plants 6-8" away that would mean the screen should be about 16-20" away from light, but that seems too far.
Well I've have to figure something out.