got a question about a 4' F54 T5 HO,what is the light penetration of a T5, I know cfl's the maximum height of light penetration is 22'', or is there no height limit with a T5 because you keep it very close to the top of plants and adjust the height as they grow. I'm using mine to start seeds and seedlings using two 4100k cool white tubes, so I thought as a little experiment I would veg with two 65k tubes, for a little while then try full spectrum with one 65k and one 3000k, and see if there is a difference, I was then going to use two 3000k and see, I read that if you use one 3000k and 4100k when flowering you get short tight nodes,was going to try it and see what happens, I got a lot of bag seed, I started with a pc grow box, It worked ok for the first couple try's, then I built a 2' x 2' x 2' grow box with 10 26 watt cfl's, it works great during the winter in the small room I'm growing in, but during the warmer months it's a little to hot, so I thought I would give T5's a try cause I can use fans to move air better then the 4 pc fans on high in 2' box.not ready to vent and filter yet cause I'm thinking of my going mh/hps and then will have to vent and filter, but not going to happen for a while