Note that if they aren't HO (High output) they wont be nearly as good as if they were, as HO flouro's are great, but just like using any regular tube a regular output flouro isn't gonna be too awesome. I think the 2' and 4' t5's are made in HO, you can check if yours is by reading the label on the bulb.

Hope that helps.

exactly right.. the HO are much better.. mine were HO full spectrum..

as for bright.. plants and humans take in light differently.. HO full spectrum T5's are nice for veg.. my 4 24watt 2 foot HO full spectrum lights veg some nice plants..

last year I had 60+ clones under them and 2 grolux 40watt wide spectrum bulbs. They had no problem and most reached 6-8 inch's in 5-6 week's.. the ones under the grolux were a darker green and the ones under the T5's were a much brighter green..

and this year I started all my veggies and 5 plants under just the 4 T5's and they rocked... especially after i took out the veggies..

spectrum is more important then lumens i think..

6-8 inch's in 5-6 week's well i hope so!
do you have the t5 becouse of money or you don't want the heat of hps - mh?

I don't know how to post and or where to post this...but here goes (and please some direct me) This is oldg and I've been at this for a few years now and am a decent "indoor" grower;however, my plants are only giving me back about 10 to 12 grms dry wt per plt. I use 3 gal. containers with a soilesless mixture (60% worm castings, 20% perilite and 20% vermiculite. For vegging food I only use Alaska 5-1-1 and for flowering I've been using Alaska 0-10-10 (however, I've just switched to the fox farm flowering food--the 3 pk): I'm growing my second batch of PPP right now and they are on their 49th day of flowering. Any suggestions?

what is the space?
what light?

I currently use (2) 4 foot T5's that are 4 bulbs each. They have 6500k spectrum and are HO. They work great for veg. Dont use them for flowering unless you are using them for side lighting.