that chart i disagree with (is there anyone on this site that i do agree with???) i highly doubt, and i would great appreciate if stinky followed up my post, but i highly doubt u can safely place A 400w mh 5 inches from plants and it be okay... although that chart did say lumens, not heat... let alone 1000w at 9 inches, but recently i was experimenting with this and i also disagree, if u can hold ur hand their for 5 seconds without being uncomfortable its ok.... but if u held it there for... 10 seconds and it got too warm thats okay???

remember the plant are going to be under the lamp 18-24hrs a day with a simple fan to keep em cool. start out far away with a MH as i remember reading, they are not as forgiving as HPS, but rule of thumb is somewhere between 16-24 inches.. but for those seedlings start it off at 24 inches for the first 2 weeks.... as that plants grow they will grow closer to the lamp, and they themselves will adjust to the light more naturally than u moving it closer then further then closer... I HAD my 400w mh at about 17 inches from my plants, and i think it did begin burning them but i caught very soon,(the same day i moved the lamp closer) and i since brought it back a few inches and the plants are doing fine.. always remember better too far than too close. and keep a fan going on the plants. and fresh air, always.
TheXFactor Reviewed by TheXFactor on . Light Distance/Height? Hello everyone! I've been browsing the posts for a while, and although its mentioned here and there, I havent found a "guide" if you will. If there is one, point me in the way, and i'll happily read away. As for the question: Is there a general rule of thumb for light distance from the plants? I know different stages require different heights, just curious what works for everyone else. My setup is fairly small, 400w MH for veg, 400w HPS for flower. Attached are a few pics just Rating: 5