Cooltube light distance heat vs light toxicity

So here is our log: https://www.rollitup.org/grow-journals/572835-first-scrog-attempt.html

We are growing in an attic and have limited height. We have about 15 inches left between the canopy and the cooltubes. Is heat the only thing we have to worry about when it comes to them getting too close to the lights? Or is it possible that the light itself will damage the plants? I can put my hand easily right up to an inch away from the glass without feeling any discomfort. Also do you think we will even have to worry about them stretching that much more? Its been about 30 days since we switched to 12 12.

Light toxicity is a condition of the eye where basically the retina is exposed to too much light, has nothing to do with plants, as long as ventilation & temperatures are in check more light= more bud, so regarding light/heat you should be fine, as for the stretching I'm not sure, I believe it would depend on the strain.

oh cool so you cant give a plant too much light? the nodes are maybe on average separated by half inch as of right now. should i expect them to separate much more at this point in flower?

yes, you can give a plant too much light. it can cause bleaching and deformity. doesn't really happen so much with CFLs. but you can have too much light for a plant. I wouldn't expect much more stretch from your plants tho, and 15 inches is a great distance to be at.

what size light is in the tube?i run 600's at 15" and closer with movers but even without a mover im good.a 400 could be closer,a 1000 should be farther like 18-20".stretch should def be over unless its some old skool sativas,gl

They're 600's and the strain is afghan kush from world of seeds.

I run a 600 in a cooled reflector. I keep it at least 10" away or it gets too hot.