mathewscott
Active Member
Starting a 2nd grow space 2x3 how many 50w cobs would be the max to use?
Help with my math
- Thread starter mathewscott
- Start date
Prawn Connery
Well-Known Member
I'd use six. One for each square foot and even coverage.
Thundercat
Well-Known Member
Personally I would consider using 6. I know lots of guys say 30-35w/sqft is "enough" but I'm really a firm believer in closer to 50/sqft. Its been proven for years to be enough light to grow excellent weed.
Don't know why I said five, it would make a hot spot in the center.
A six pack with dimming would be great.
JavaCo
Well-Known Member
This guy here is growing with 33 watts a square foot with screw in bulbs that are only about 1.6 umol/J some of the newest LEDs released this year put out over 3.0 umol/J so if Northwood had the lastest tech @ 3.0 umol/J he would be fine with 20 watts a square foot.
http://www.rollitup.org/t/my-budget-5x5-setup.982183/page-2#post-14674329And here we are at the end of week 5. These 4 ladies are getting very smelly.
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No doubt! I hope the newest generation of diodes find their way into home light bulbs in a few years. One advantage with screw-ins is that a child can change out bulbs with new diodes in about 10 seconds, either when something better comes along, or if something dies. A child would have a lot more difficulty exchanging diodes on a 2 year old quantum board with this year's technology. Light bulbs today are ever improving (slowly though), and now put out about 120 lumens per watt. New diodes can now achieve 180 watts per watt and apparently some even better. I know that
I could use quantum boards or whatever containing the latest diodes, however with the price of electricity in my area it would take a large number of grows and likely many, many years before I'd break even compared to what I'm using today. Remember I'm lighting a 25 square foot tent with about $200 (Canadian) of LED, and darn they get cheaper every year. I could have easily spent 10 times this amount to light that area using the newest/best diodes. And I'd lose the flexibility that allows me to use very little power during each stage of growth as I explained on that thread.
As far as needing 50 watts per square foot with LED, well they'd need to be kept really far from the plants, but you'd get great penetration. My silly bulbs do bad things to my plants if they're closer than 18". 24 inches seems pretty optimal for me. So unless people are using the most inefficient diodes in the history of LED (like around the same efficiency of HPS), 50 watts/foot might be a bit overkill. Frankly I'd just use HPS in that case - nearly the same efficiency, MUCH cheaper upfront.
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Thundercat
Well-Known Member
My current grow is at 62.5w/sqft and I get dank dense delicious nugs. If I had the chance though I would still add some led side lighting all the way around my room to really get the most out of the plants. It's just not practical right now though.
Thundercat
Well-Known Member
Me? I currently have 1k hps over. 4x4 tray. Sitting 12-14 inches from my canopy in a nice wide air cooled hood.
I'd love to add some Samsun stripes or maybe QBs around all 4 sides to really round out the light coverage and penetration though.
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Prawn Connery
Well-Known Member
50W sq/ft is what I've been using, too. You can use more or less, but you've gotta start somewhere. And you can always dim the driver.
Rahz
Well-Known Member
I don't mean how many. I mean what brand and model number are the cobs? We can figure out what the max is depending on which cobs you use, and also what is perhaps a more reasonable light level. Figure out the PPF you will be providing and you can determine the DLI.
JavaCo
Well-Known Member
Yeah I don't know why people seem to get upset when you show them science that they are using more light then needed. I dont know why the only thing it would do is save them money on the electric bill. But yeah you are already invested in a light now plus you can just slap newer more efficient bulbs in as needed. They will even be more efficient and cheaper in years to come.No doubt! I hope the newest generation of diodes find their way into home light bulbs in a few years. One advantage with screw-ins is that a child can change out bulbs with new diodes in about 10 seconds, either when something better comes along, or if something dies. A child would have a lot more difficulty exchanging diodes on a 2 year old quantum board with this year's technology. Light bulbs today are ever improving (slowly though), and now put out about 120 lumens per watt. New diodes can now achieve 180 watts per watt and apparently some even better. I know that
I could use quantum boards or whatever containing the latest diodes, however with the price of electricity in my area it would take a large number of grows and likely many, many years before I'd break even compared to what I'm using today. Remember I'm lighting a 25 square foot tent with about $200 (Canadian) of LED, and darn they get cheaper every year. I could have easily spent 10 times this amount to light that area using the newest/best diodes. And I'd lose the flexibility that allows me to use very little power during each stage of growth as I explained on that thread.
As far as needing 50 watts per square foot with LED, well they'd need to be kept really far from the plants, but you'd get great penetration. My silly bulbs do bad things to my plants if they're closer than 18". 24 inches seems pretty optimal for me. So unless people are using the most inefficient diodes in the history of LED (like around the same efficiency of HPS), 50 watts/foot might be a bit overkill. Frankly I'd just use HPS in that case - nearly the same efficiency, MUCH cheaper upfront.
mathewscott
Active Member
Thanks. It's a DIY I can configure my setup any way I want
