My seeds should be sprouting in the next day or so. Once they do, I am putting them under a 400 watt MH. I was just wondering, how far should the light hang from these sprouts?
You really shouldn't be using an MH system on new sprouts. I would sprout using CFLs and T8 florescents, and then switch to MH after the first couple of weeks. MH might be too intense, but if you choose to use it anyways, I wouldn't go any closer than 20", but that's just my opinion.
have 2 400 mh's, once my seedling sprouted i kept the light 20-24inch away at first, they are almost 3 weeks now and its down to a foot now
Put your hand where the plants are for a few minutes. If it´s too hot for your hand, it´s too hot for the plants.
Should I have my sprouts under a humidity dome, or should they be under the direct light? Right now I have them in a dome with my light about 22 inches above the rockwool cubes. Here's how they are lookin:
Since they're seeds, no need for the dome so much. Listen to what TreeOfLife said in this case. 20 - 24 inches to start, and then take it down to about a foot. I remember a link to a chart which shows this, but I don't remember what thread it was in. I'll start saving images of these things eventually so I have them available. Heat's your only concern, and ventilation will help with that as well. Cantharis had a good idea as well. If it's too hot for you, move the light until it feels comfortable, and then move it up a few inches from there.
maybe these will help ya, they saved me some trouble MH-Light Distance Chart HPS- Light Distance Chart