Seedling Proximity To Light

I always start my seedlings under 2 22watt flourescent tube lights and am trying to figure out how far away it should be from the bulbs. I typically have the seedlings about 10 inches under the lights and any closer the leaves start to curl. But I feel like the plants are slow to grow(I know all seedlings are slow) so I need to know how close I can go to get maximum growth without stressing the little plant out...Thoughts?

put them couple inchs cfl and fluresent wont burn inless it touchs. cfls are great for seedlings and veg but i wouldnt use them for flower h p s lights are best for flower. i had alot of strech when i left the 4 foot light had about 8 bulbs overthem though it would be enogh but it wasnt so i dropped it will it almost touch the leafs they grew like crazy when done. finish size was about 50 inchs 4 plants about 190 grams 1st grow. i do hydro so i check it like all the time so it was easy to watch the light and hight from plants.

With 4 ft tubes its often fine even if the plant touches the light. The heat is so diffused it doesn't hurt it.

iron joint said:

With 4 ft tubes its often fine even if the plant touches the light. The heat is so diffused it doesn't hurt it.

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Then what causes the leaves to curl when I get it any closer than 8"?