Planning Ahead

I have a 4x4' using a single 1k hps. I think I'd rather have 2 600's but trying to stuff 2 big hoods in there would be a pain. Everyone tells me 2 1k's would be too much for a little 4x4' tent. That would be nice tho!

Hth

 

A single lamp works more efficiently than two lamps of half its wattage. For example, a 400w produces maximum growth in a 2.25' square floor area. If you place two of them side by side, they'll cover a 2.25x4.5' space. If you instead got an 800w lamp, it would cover at least a 4.5x4.5' area. You'd get maximum growth in an area that's twice the size of the two 400's but with the same power usage.

If you really have to use a rectangular area like a 4x8' space then two lamps are of course the way to go. Four feet wide is just between what a 600w and an 800w can support maximum growth in. You can stretch the light of a 600w half a foot beyond ideal and still have great plants. Or, if the extra electricity & heat aren't much of an issue for you, you can use 800's for each 4x4 area and have light to spare. It's up to you. For lowest temps, go with 600's.

 

It's a little tough to answer that question because without a side by side comparison using the same strain, food and techniques as you, all someone can do is give an educated guess. With sufficient food and proper care, you might see a 15% increase in yield when stepping up from a 600w. Whatever the exact percentage of difference would be, you'd see the same increase whether you used an 800w or a 1000w because the 4' square floor area is within the area size that an 800w can produce maximum growth in.

You should ask yourself certain questions and you don't need to post the answers here. Is this for personal or profit? Do you expect to expand your operation in the future? Could you expand the dimensions right now, even just a half of a foot? Will you be using a good centrifugal blower for lamp cooling?

If the grow is just for personal use then get a 600w. Anything larger could regularly produce a hell of alot more bud than you and your best friend could smoke. If it's for profit, you plan to expand the grow later on and you'll end up using some quality cooling equipment then get a higher wattage lamp.

Personally, underneath a 600w I use 3x3 plants for a total of nine in 5gal buckets. These can be touching each other for a minimum size of 3x3' or the 600w can support slightly wider plants trained to have a few more colas in a 3.5x3.5' growing area. These nine plants can yield anywhere from nine ounces to two pounds of trimmed, dry bud at each harvest, depending on how heavy the strain is.

Under an 800w, I would flower 4x4 plants in 5gal buckets, for a total of sixteen that yield one to four pounds at each harvest.

Also, make sure you really want a tent before buying. Premade ones are completely unnecessary but occasionally helpful. It's much cheaper to DIY some walls and a top using wood, cardboard, sheet rock, etc. That's assuming you actually need even that much- plants can grow fine just sitting in a room with a lamp overhead. A DIY grow area will always be the perfect size for you with everything exactly where you want it to be.

 

The usual formula for figuring required cooling is CFM = (3.2 x wattage)/Difference in Fahrenheit. The difference in Fahrenheit is the maximum increase in temperature you're going to allow. If you're fine with a ten degree increase in temp then you'll want 320 CFM. This is just the minimum CFM for a roughly ten degree temp increase. It doesn't take into account reduced airflow due to length and bends in ducting (more on this at bottom) or filters. It also assumes you're cooling the bulb by drawing air from the grow area and exhausting it outdoors or else somewhere that won't further affect grow room temps.

Myself, I grow nine months out of the year and take a vacation from it every summer. I cool lamps by drawing cold air from outside. This way, even less CFM is needed because I'm cooling with air that's already cooler than the grow room's temperature. Most of the time the lamp's glass is cool or even cold to the touch.

You can't cool lamps too much, excluding grows in near arctic temps. Err on the side of too much airflow. Get a quality centrifugal blower to use for just the lamp. Such nice pieces of equipment move air at minimum decibel levels and should last a long time. Pull air from the coolest place possible and exhaust it outdoors- a well-vented attic is a great place for this. If you draw air from somewhere other than the grow area, you probably won't need to worry about any odor, at least as far as the lamp's cooling air is concerned. The plants will still need some fresh air but only very little compared to the lamp's airflow.

While you don't need to start out with one, getting a dust filter for the cooling intake at some point will keep both the lamp & fan clean. A household central heater filter can work well but there are also other options that won't significantly decrease airflow. Multiple filters allow even more air through without the flow decreasing.

Fantech is one of the better fan companies and sells excellent products. On their site click commercial and then inline. Here you'll find CFM ratings, both maximum and with various amounts of resistance, as well as electrical figures and other info. Just download the brochure for each fan series and see what fits your needs best. Get a blower of the highest series that has your desired CFM for best quality and lowest noise. Get one of the lowest series for least cost.

 

Certainly. Once you've got a lamp of a given wattage, by all means make the most out of it. A 1000w can support strong growth in a 6' square floor area. I always create six colas per plant and they just fit inside the diameter of each 5gal bucket (each cola's roughly 4" wide trimmed & dry), which lets me place each bucket so it's touching its neighboring buckets. In a 5x5x7 tent, you could easily grow 25 plants in a 5x5 pattern. Since it's still a smaller size than the maximum a 1000w can support, every one of those 25 would get plenty of light. I would definitely set up a 5x5 plant pattern if I used a 1000w in a 5x5x7 growing area. Even with lower yielding strains, you should expect at least 1.5lbs from each harvest.