Can u burn with just intense light even if the heat is properly handled?

stupid the sun is strong but wondering cause i think its happening the room is warm but area under the lights is circulating and the canfan is going

what kinda temps are u looking at?

no.......its the heat that burns, not the light.

it is possible, yes. give us more details about your grow and we can try to help you. pics would make it easier too.

why dont u try it br() ! if u put yer hand ontop of da canopy of da plants and yo hands can chill der without bern iz ok for joor tomatoes!

heard of bleaching from light, but not burning. Burning seems like it would have to be a heat problem.

Then wh do people start with T5's and not a 1000w MH on seedlings?

iamaaror said:

Then wh do people start with T5's and not a 1000w MH on seedlings?

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because u can get the light closer to the plant without burning... or bleaching.. and the mh will have to stay around 18-30 inch away .. causing the seeds to stretch... u can do it.. but if u want bushier plants with less internode stretching grow under t5s or cfls realy close with fan on em.. and then around 12inch to 16inch put under mh... wen i used my 1000w mh in a air cooled hood i put it arund 12 inch above plants.. and they were fine.. but stretched way more then i wanted .. so i use t5s now.. and cfls.. iuno what it is.. but im going to be trying thsoe new metal halides.. with added blue spectrum for bushier growth.. maybe ill get a 1000w and put it on the light mover when i get my place.. and then just have it going across the room back and forth.. with some T5s on the sides.. for lighting.. but anyways.... most people i know start with t5s cause u see less stretch. then with bigger hoods and bulbs.. and another thing... u can save electricity also..

There was a chart somewhere I used to use for reference, you might be able to good search it, its from another forum. But the jist of what is said for rules of thumb is that assuming heat is controlled, you never want a 1000w closer than 12" to any part of the plant. And for optimal lighting, you don't want the furthest growth further than about 32". These numbers are approximate and off the top of my head however.

I don't remember where I got this info from, but I use a cheap light meter, and hold it over various areas of where I want light, and make sure I'm getting 2000-2500+ lumens on that area at least. Keep in mind this is with a 1000w HID, I don't know the standards for lumens on T5s. When I use t5 for anything but seedlings, I put it as close as I can without physically touching the leaves with the bulbs.

You can get lumen burn. If your light intensity is to strong or the plants are to young and get to many lumens it can and will bleach a plant. (Look up light bleaching.) Its happened to me. I had to back my lights off a bit.

iamaaror said:

Then wh do people start with T5's and not a 1000w MH on seedlings?

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I started my seedlings under a 1000w MH, however; I grew them from seed in their final pot and turned the lights on before they came out of the dirt. They didn't stretch, they filled out pretty well too. 1000w is obviously not necessary that early on, but if thats what you had to work with, then you'd just back it up to about 3 feet or so and they'd be fine.
T5s are better for the electric bill.