I have a 48”x48” grow tent. My total watts from the wall is 500w for my 2 cobb led lights. They’re 250w each, so that’s 4.608watts per square inch. Is that acceptable for dense buds? I will be feeding fox farms nutrients with fox farms ocean forest soil as well.
Hello. Welcome looks like your off to a good start. I don’t know much about those lights. So many.
The light is a little weak. It will be ok for veg. Your fans draw some of that wattage. Just do get crazy. Two plants should do nice. I would get them in the corner some. So you have the reflection more.
Hello @AmnesiaHaze , watts per square foot is an old school way of measuring light mostly the bulb lights. Leds are so different from one another that with the best ones you could have 30w/ft² and do good where some lower quality leds you might have 75w/ ft² and barely squeak by. There are some pretty good cob leds out there but my experience with them is very minimal. I’m going to guess and say you will need more light to flower your entire tent but @dbrn32 is the light guy and will come by since I tagged him and he’ll be able to get you pointed in the right direction
I’m not familiar with efficacy of your lights, so hard to say. 500 watts of really good leds is pretty solid.
Thanks everyone for the quick responses. They are 1200w lights each one is 1200w equivalent, and draws 250w from the outlet on each one totaling 500w, the fan is another 140w it is an inline 6” fan with carbon filter.
I’ve grown 3 white widow autos with these lights once using crappy soil and fox farm nutrients and they were almost 40” tall. I think it was because my lights weren’t close enough so they stretched. The buds were thick too I just want more density to my buds, maybe cooler temperatures can pull more density?
Im growing 4 White Widow Autos next. I’ll be using fox farms ocean forest with fox farms nutrients this time I’ll post pictures of how they do to show everyone.
Equivalent to 1200 watts of what though? Hps and metal halide run about 130 lumens per watt or +/- 1.6 umol/joule. 5x either would be 650 lumens/watt or 8 umol/joule. Neither is currently possible. I suspected 1200w equivalent is an unfounded arbitrary number the manufacturer throws out to make them seem better than they are.
What was your dry harvest weights from previous grows?
I believe it was a HPS/MH equivalent advertisement when I bought it off Amazon. They did show charts and graphs of the reds and blues the light gave out it was pretty trustworthy. From the last run I had 10oz dry from 3 white widow autos.
If so they are fibbing. The best leds in the world right now just aren’t that much more efficient. If you get the best of the best and run at reasonable current they are about 2 to 1 with hps. Those fixtures are all in the $1000-$1500 range right now, as far as I know.
The growers i know that using this kind of technology in 4x4 are usually in the 1-2 pound range dry out of a 4x4. That isn’t hard data, as experience and other factors will play into yeilds as well. But is one of the main reasons it’s difficult to say how many watts you need to have a successful grow. Black dog sells their lights for bookoo bucks, and independent third party test data shows their lights at lower ppf per watt than hps.
Appreciate the feedback
And FWIW your original question answered is: .217 watts per square inch or 31 watts per square foot: good enough to veg, not quite enough for dense flower. You also need to factor in coverage area of each light: I’m guessing it falls off pretty hard once you aren’t directly underneath it.
Hope your wrong on this🙃 no disrespect buddy, I know you know your way all the around these plants💪 Dalightguru had me build at .180. so we will see. The great flip is tomorrow so not much longer and I’ll have my answer.
And thanks for mentioning tds reference solution in another thread the other day. I ordered some and my pen is 60ish on the low.
Many of us have had and used lights similar. If you have enough of 'em they’ll grow good weed. Like @dbrn32 said; a yield of1 to 2 lbs under enough light is about right.
I’m running around the same per square foot wattage, but using custom LED fixtures that deliver 12 oz per plant reliably.
That’s strong numbers. With all y’all’s guidance I’ll be there soon.
@Myfriendis410 we will see how my next run goes can’t wait
Sowed in are 4 white widow autos, let’s hope they all pop up around the same time, most do some dont.
Little update I have all 4 autos now breaking soil they’re just popping out their tiny heads.