I'm building a 30x30x48 grow box and was wondering if a 400watt mh/hps will be too much heat in that space. I also have 2 two foot t5 fixtures for additional side lighting if needed.. I will have 2 four inch pc fans for intake(rated at 60cfm each) and have a 170cfm duct fan with a carbon filter to exhaust. It will also be in a basement that doesn't get over 70 degrees. I plan on doing 9-12 plants. What do you think? Should i use a lower wattage or even cfl? Or should I be ok?
400 watts to much for my space?
- Thread starter 420forme
- Start date
racerboy71
bud bootlegger
i was just asking my hydro store owner the other day about upgrading to a 400 watt, i now have a two fifty, and he told me that if i don't have atleast a three square foot area, than the four hundy maybe too much for my area.. by looking at your size, i would think that you would be right on the borderline of a two fifty or a four hundred, and the choice would be yours.. the heat of a four hundred is def something to think about as it is alot more than a two fifty.. so long as you have good venitation and all, i would think you could probably get away with the bigger sized lamp..
Yeah that's close. I'm gonna use a sealed, air cooled Hood and remote ballest. That should cut the heat a bit.
What kind of output does a 250 hps have?
racerboy71
bud bootlegger
lumen wise you mean? i think one will push out around 25-30k lumens... i only grow around four or so nice sized plants under my two fifty... i also use a few small cfl's for around the sides and bottoms of the plants... i get around two ounces per plant using the two fifty, which is plenty for me.. i only have a small closet grow, about maybe three feet wide, by around two or so deep and six or so high..
it sounds like if you use the air cooled hood and all, you should be able to get away with a four hundred.. the more light you have, the more you will yeild, so long as your not over doing it with the added heat and all, but i think you should be in like that, lol..
gl...
ink the world
Well-Known Member
I flower in a closet about the same size. I use a 400 watt HPS thats got an exhaust. I also exhaust the closet and have an intake. My plants can touch the glass and not get burned now.
Thanks for the replys everyone.
Well I was planning on having 2-60cfm fans pulling fresh air into the box and a 170cfm inline fan pulling air though a carbon filter that will be in the box. It will also be pulling air through the light reflector then out. I really want to try a 400 so I hope it will be enough to keep it cool.
One other question, since its only 4 ft. Tall should I just mount the fixture all the way at the top, or hang it so its lower?
racerboy71
bud bootlegger
i would try and keep it as high up in the space as you can.. four feets not all that tall and once you add in the height of the pots you will be using, it doesn't give much room for vertical growth, but it can be done without any issues. you may have to look into maybe lst or supercropping as the plants get older... i would also suggest sticking with a mostly indica strain to make sure your not gonna end up with a monster...
Silky Shagsalot
Well-Known Member
the only way to really find out is to put the light in there and monitor the temps. i'd forget about the additional t-5's on the sides. just use some good reflective material (astro-foil.) to help with cooling, think about maybe adding some passive intakes on the bottom.
I do plan on trying some lst and/or topping with the first run. Also gonna get some real strains, no more bag seed.
Where is the best place to put the thermometer, right at canopy level?
Right now I have one at canopy level and one near the top of the box and they are usually within 5 degree or so of each other(cfl's thou).
Thanks for the tip on passive venting, I might as well add it, cant hurt.
sixstring2112
Well-Known Member
I'm using a 400hps & 4 26 watt cfls in a 26"x 48" x 52" high with 1- 4" computer fan going in and my light on a 4" exhuast with 160cfm. my room temps are right around 70f and the grow box stays right at 80-82F hope that helps.
Yeah that helps, the more I read I think my space is still to small to run a 400. I guess I will go with the 250, it seems to be rated good for a 3x3 space which is about what I got. I can always add the t5's for a little extra.
You made the right move...a 250 is nice for a 30"x30" space.
The 400 problem is heat. And you have to keep it 24" from the tops of your plants to keep them from burning. With a 250, your temps will be in the 70's. With a 250, you can be battling 80's.
Top your plants for 4 or more leads. You want a thick, even canopy about 12" under the lights.
The 400 problem is heat. And you have to keep it 24" from the tops of your plants to keep them from burning. With a 250, your temps will be in the 70's. With a 250, you can be battling 80's.
Top your plants for 4 or more leads. You want a thick, even canopy about 12" under the lights.