so i know i've asked before, but how far away should a 400 watt mh light be from 12 day old plants? i've been told just to use my hand, but with my temp gauge, it reads high 80's at the plants base, and the light is about 2ft away right now. should i move it closer or away with the high temps? how many inches do you guys keep your mh lights from plants?
From what I understand, 2 feet is fine for an MH light. Moving it closer or farther isn't going to do much for your temperature though, since that's the temp of the air in the box. If it's in the high 80's I'd suggest increasing your ventilation, because moving the light enough to help would probably make it too far from the plants.
Hey there RichieRich (loved that comic!) 2 feet as actually perhaps a little too far. The further you place your light, the less lumens are getting to your plants foliage. Your 12 day old kids will thrive if you place that light about 12-18 inches away but of course in order to do that you will need to upgrade your ventilation as mentioned by BKKG. What you may want to try is go buy a $15 fan and blow it directly at your MH bulb all of the time, this should cool the light a little and hopefully disperse some of the heat created by it. Peace and happy grows!
i have a fan right now blowing directly at the light. The ventilation is definaly something i have to work on, just gotta get paid. im thinking that if this grow doesnt workout in my closet that im going to save a lil money up for a while and build my own box out of lumber, and paint it. or wait til winter and do a few big SOG grow while its cold outside to control my temp issues inside.... hmmm...only time will tell. thanks for your fast help! you guys here on GC rock! lovin this place.
Okay, Okay totally understandable I try to keep costs to a minimum as well. Here is another option for you, something I have done before since I live in a northern climate I take the fresh air from outside and bring it in (excellent source of CO2 for the plants as well!). Go buy a 12" fan and some 12" ducting (trust me ducting is cheap at your local hydro store or go to a Home Depot or somethin') when you get paid. You should be able to keep it around $50. Duct tape the ducting around the front of the fan (don't try to make it fit perfectly cause it wont, just make sure its secure). Now place the fan far away from your grow room preferably right next to a window or some sort of fresh air source and blast it as fast as it can go. What you are doing here is not only hopefully lowering temps by about 2-5 C (approx 8 F) but you are also injecting your grow room with fresh air/CO2 which is VERY important if your temps are too high. Do this and you should have a successful crop even with temps in 80s assuming that your plants will get a break in the dark period (hopefully low-mid 70s if you can) Keep workin' brotha this shit takes a lot of guess & test (knowledge always helps too)...
thats a good idea thanks daganjamonster! i'll try that, im already planning on some ducting to exhaust heat away from the light, and for a better intake, and to keep the intake and exhaust light tight. they get down into the mid 70's at night for 6hrs. i just added a bottle of homemade co2 from water, yeast, sugar. hope this helps them handle the higher temps better.
Glad I can help! Of course the more CO2 you give em' the faster they will grow, just remember they don't use much CO2 at night so add it when the lights are on. Brotha, if you are getting temps low at night you gots nothin to worry about! See the thing about temps is growth stops around 85 F but they are still taking in energy from the light. At night is when all of the magic will happen for you when they respire. There will be times when you look at em' in the morning when the lights turn on and you'll say "gosh did they just have a spurt overnight... yup indeed they did" Of course flowring is a different story my friend... you gonna have to try your best to keep those temps down or you'll end up with really airy, fluffy buds. peace...
when i start flowering and there on 12/12, ikm going to try keeping the lights on at night, so its cooler, and off during the days....i'll get all the lil details worked out when its time.