Clipping them leaves may stunt them even more or at least slow down their growth , I just let them die and fall off naturally, I look at it this way .. "there isn't anybody in nature to clip off dying leaves"..
I'm not certain but I'm thinking the yellowing leaves would be more due to higher humidity, the lower the hum is better, so i've been told.. only thing is with the humidity being too low is that it dries out your soil too fast, before the plants get what they need and this forces you to water more often. (in theory)
You can find ph testers at your local hot tub outlet, they carry them all seasons, they also sell them at hardware stores, walmarts, ebay etc.. for hot tub purposes.
Try using computer fans, I have examples of them in my journal, if interested skim through it, find the images and the information on them...
I'm thinking you could grow 4 - 6 small decent plants using the 250w plus cfls, what's stopping you from getting a 400w or higher?
Peace!