Quick question

My tent is 4L x 2Wx 4H. I have 1 400 watt hps for flower going at the moment. 400cfm fan and scrubber are on the way.. What would I need to do to be able to run another 400watt hps? My temps are fine so far but it's a bit hotter at the canopy tops.. I know another light would really jack up the heat so what would I need to do to make it sufficient?

Wish I had good answer for you, but If your 400w covers about 3x3 you're about maxed out. You could add larger CFL for flower, but that will create heat, too. I have 2 tents; one is 8x8 and the max they suggest is 4x600w. The other is about a 5x5 and I could prolly get away with 2x250w, but I don't do that. I don't think you'd gain anything with 500 watts. If you think you can cool a 600w bulb you could try it, but with 2 feet width that's a problem. Even if you turned the tent on it's side it wouldn't work out. Best suggestion...save up for a larger tent.

If you haven't looked at the 400 watt club, take a look:
https://www.rollitup.org/grow-room-design-setup/61539-400w-club-show-off-your.html

Maybe someone else will advise you differently. Good luck and have fun with your grow.

you are really limited in height. I have the same 4x2, but mine is 8 feet tall. I have a 600 watt mh/hps with an inline fanning pulling air directly from outside, through the hood and out the ceiling. Then i have another fan connected to carbon scrubber and out the ceiling, with passive intake. My temps stay in in 60's to low 80's...I do keep the surrounding rooms very cold, to help keep temps down.

Thanks for the detailed answers!
i was thinking more of putting the lights side to side instead of back to front. The height is perfect for me as I'll be doing more smaller plants instead of a few larger ones.
I was thinking, and hoping, that a large cfm fan pulling in cold air would be sufficient in keeping temps lower as well as the cfm and filter pulling out some of the air. Would it make a difference if I got one of the cool tubes for the second light?
My only option I'm guessing as hooking up a small ac on the outside and venting it inside aye? Cause I'm not particularly up for that..
I do have a 4' 4 bulb t5 fixture I could toss in as side lighting but I think that would almost be just the same temp wise as an extra hps?
What if I were to toss in a 150w or 250w hps instead of another 400? Or if I just got the 400 and ran it at 50 or 75% most of the time(when I can keep an eye on temps) lol

Run aircooled lights

Adding another 400 might make temps way two high. I had two 600s in a 5x5 and it was hitting 95. I would say run aircooled lights add a 250 instead of a 400. SOG and you can hit some good yields in a small space with 650 watts.

I was really ripped when I rambled on LOL. It's 2:30 a.m. and I woke up thinking WTF did I write? LOL

The point is that you can run as much light in an area that you can cool, period, but you will reach a point of diminished returns. Air cooled reflectors are advisable to ax out your space as well as sog, but it'll be crowded in there.

I'll also stick with one of my original cogent thoughts LOL....save for a bigger tent.

I'm just trying to see what my best options are to keep the temps down really. I know 800-1000watts wouldn't be overkill in my tent and I would have definitely got a bigger tent but I had to go through hell and back to convince my fiancé to even let me have this one lol!
I have a few of those random wake ups as well lol. Sometimes because of work and what I might have said to the homeowner or my boss and sometimes because I just flat out forgot to write something important out lol.
I don't mind crowded as long as it is being used properly and every bit of the girl is putting out proper buds
I have been having issues with my sweet god girl so she's far behind in flowering :'(
Tuesday is week 7 and she has at the very best another 3 weeks to go.. 6-8 week flower time not so good when she gets nutes locked out
My critical kush is supposed to be an 8 week strain but she will likely be 9 and my strawberry cough is 9 weeks but she MIGHT come down in time.. No issues with anything but the sweet god but still not going to be done when they are supposed to be which is a shame cause I wanted some Xmas herbs lol

Flowering times are only an estimate of earliest possible harvest times.

400w in that room is plenty.

I have used 400w over 4 plants and I can pull 16oz. 2ft tall plants in a 3x3 footprint.

I would work on keeping your plants healthy and green. This way you'll achieve the yields your looking for



J

I am with jon above. ONE 400 or 600 with side/corner cfls if you think you need it down the road...Then get good at training your plants and knowing their genetics to keep things small. Problem with 4 feet is you need to factor for space for your equipment (Light, hood, exhaust, wireage, pots/rez, soil/water, free space for air movement), Once you get that in there you are going to have space for 1 foot tall plants at best. You sure you can't gain a foot or 2?

Here in my 4x2x8 shortly before flower. I have topped and trained these plants. The 3 plants (2 middle, 1 back left) will be 5 weeks old when I flower. They are probably 8inches to maybe a foot at that point, but will end up at 2.5 feet tall (Not including the pot). I will drop the table they are sitting on a few weeks into flower so I dont have to raise my light all the way to the ceiling. I have had it up there but things get hotter because airflow is not as great with all the folliage and small space. I guess I am trying to say I have never had a problem with having too much space...just problems with to small

Beauty room! Very beauty! Right now my girls are about 3feet, with out the pots lol. My strawberry couch is level with the bulb so I've had to do things a certain way in order for her to not burn. My light had to be hung with zip ties to keep it so close to the roof. I really didn't expect my girls to stretch as much as they did as I've never worked with these genetics and was not able to find much info on them either. To save myself from that next time I'm just going to do a bunch of girls and flip them at a little less than a foot in height.
I would love more room but when you are engaged to a gorgeous Latina model and she gives in a little, you take it and run with it haha.

thanks, I have always grown in tight quarters. This is room version like 6.0. Moving to the air cooled hood changed a lot of things. Temps are 10-15degrees cooler.

Knowing height is tricky because it shoots up so much in the first 2 weeks of flower. I ALWAYS top and train, and flower at 9 inches give or take. Sativas only veg like 3-4 weeks because they are so leggy.