Need Help Determining Wattage for a Small Space

[ookiimata]

The new flower cab I built is smaller than anything I've grown in before. 36in length x 16in depth x 32in height. I'm going to go vertical HPS with DIY RDWC. The bulb will be in the middle of the cab inside a cooltube with intake at the bottom and exhaust at the top, the plants arrayed in a rectangle-ish square around the bulb. Vertical scrog and I'm also hoping to screen the top and train the plants to crawl along it for some extra length. The grow area will be sealed except for the door and I'll use CO2 to combat the (almost inevitably) high temps. The room it's in always has the windows open (and AC running during the summer), with a fan on one window drawing air in (I close this window during the summer and put the fan in front of the AC vent instead) and one window with a box fan exhausting the room. That's just my day to day living setup because I hate heat. I can use any size fan to exhaust the cool tube. I have a 6in vent fan lying around already, can also buy another one if need be. Flower cab is light proof and insulated with foam sheets. If humidity in the cab proves to a problem I'll wire up an exhaust fan controlled by humidity level.

The veg cab is the same height, but over 20" deep and not as long. I'll probably do 6500K CFLs in there (never used CFLs before). I'm also considering making the veg cab just for for mom and clones, harden off the clones, then put them in the flower cab with MH (digi ballast) until they're 8-10". The only reason I'd do that is to prevent root damage in moving the plants from one cab to the other because it's such a small space, and if I decide to do some serious training.

So I'm wondering if with those dimensions, and giving you guys a rough idea of the environment, do you think there's any way I can put a 600w in there without turning it into an oven? Remember, vertical with a cool tube. Cervantes says going vertical loses some lamp brightness, plus I hate using 400W-ers when 600W-ers are so much more efficient. The efficiency is really the thing that's making me want to put the 600W in there. I'm also wondering if, even if I can control the heat, 600W will end up going to waste because the plants can only get so big. I can modify the setup to train them tight if I use the MH in there to veg. I was also thinking about getting the 400/600 Select a watt and using 400 MH to veg then 600 HPS for flower. That option would give me the ability to go down to 400W flower as well, but I'm still not sure if the 400 mode actually pulls 400W or still pulls 600W and just gives the bulb 400. I'm not going to waste 200W to run a 400W bulb.

Thanks in advance guys. I'm hoping some of you have more experience with small spaces than I do.

 

[xX Kid Twist Xx]

that place is so small shorter then 3 feet. how big is your pots/tubs or whatever you are suing gonna be? is that your total hieght or is that the higeht minus the hood or bulb? i would say go with a 250 watt bulb for hps youd be right around 30 watts a sq foot. with a 400 your over 45 watts a sq foot wich is better. your hieght is also a big concern for me.

 

[ookiimata]

Yeah, man, the height sucks. I haven't grown in several years, but I love growing, so when I built myself a new desk I figured I'd build it in such a fashion as to give myself two small cabinets for a grow. 32" was about as high as I could go while still making it useful for a desk as well. The build came out great and the cabs are really sealed and insulated well. I'm not really stealth, but people do occasionally come into the room and I would obviously prefer they not know what was going on. I tell literally zero people when I grow.

Because I'm going to hang the bulb vertically, I won't need a hood or reflector. My hope is that this will help with heat buildup as well as give more light 360degrees because I know I won't be able to get the normal desired wattage. I have a aero/RDWC system that I've built before that I'm going with. It will be 8-10" high, so those inches will be subtracted from the total allowable plant height. I've gotten away with 8" in the past with small plants (giving them more width instead) but I'd like at least 10". I've got a few sample buckets I've been playing around with for layout testing, and they're all 8-10" high.

The way I see it I'm going to have to vertical scrog/lst them with more leaf defoliation than I would like (although there are many people that claim various things about removing leaves being a good thing, I usually do it at a minimum rate) to get some good yield. This is just personal stash growing for fun, but I don't want it to be inefficient as far as power usage v. yield is concerned.

I've built a few rooms in the past, and done quite a few reef aquarium setups, so I'm good enough with plumbing and figuring out workable solutions. My real concern is the bulb heat. The ballast will be external. It's definitely going to be alot of testing involved as far as training/screening as well as number of plants. I'll probably do a test grow with a couple plants in soil the first time just to get an idea of what the cab is capable of (and more importantly, what's it not capable of).

 

[Tynesharpskin]

can you not use a cool tube? might sort the heat concerns with such a small room

 

[ookiimata]

You think not using the tubes would be better as far as heat is concerned? I've never used them before, but I imagined that in intake at the bottom of the tube pulling cold air from outside the cab blowing up over the light and an exhaust at the top kicking the air out of the cab would keep temps well in control. I'd prefer to not use the tube because I'd get more lumens. Perhaps bare bulb with a 6" fan underneath it blowing up, then a couple exhausts at the top throwing the air out of the cab?

I've also decided I'm almost definitely going to go soil for the first couple runs until I get a feel for the space. I don't want to have to worry about cooling the res if temps turn out to be hot. The res would have to be outside the cab no matter what, so avoiding having a tank of water sitting under my desk would be a plus. Leaning toward a dimmable 400W quantum right now, mounting the ballast outside the cab.

 

[Tynesharpskin]

im saying use one it'll sort it right out and the lumen loss is neglagable if you use a quality one