You can keep your T5 abt 3 to 4 inches, I use T5 2ft,4 bulb also, but keep an eye on them, they will start to sprout fast, yes, you should have constant air circulation, start with a small fan, enough to "jiggle" the stem to strengthen them, best of luck with your grow, and don't worry so much, your plant knows what to do, just feed them and don't over do it.