T5 Light Proximity to plants

I started 9 sprouts in a drip system with 1/2 strength nutes with a 2 ft 2 bulb shop light 17w each and ater 2 weeks they have grown to 3-4", I just switched to a 8 bulb 2 ft pioneer Jr VIII T5 fixture from cheap hydro. I think I had the new light too close (the shop light was only 4 ' off the plants) and they started to wilt so I moved it up to 18" above the tops and they have made a pretty good comeback... Can someone help with a ruling on how much distance for this new light??? It has 8 VitaLume "grow" "cool" bulbs. I have the drip system set to feed 3 times during daylight hours which is on for 20hrs and off for 4hrs. Opinions??? Advice???

Long Time Toker

2 to 3 inches.

Like I said.. I had the light within 4 inches and the plants stated to wilt, perhaps a few pics will help..

Just stick a thermometer under the lights. When the temps stick around 75-85 degrees F then you know your distance is good.

so how did you like the pioneer jr viii? i've been looking into a new set up... i was gunna go for two satellite 4 or two of the pioneer jr 8's.