stawawager
Well-Known Member
Hi. Is 2500 Watts overkill for a 4 ft x 4 ft area?
Thanks.
Thanks.
Max wattage per square foot...
- Thread starter stawawager
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stawawager
Well-Known Member
Thanks, glad I asked. Just want to keep them happy and content and especially not overheated!
Profound Bastard
Active Member
Can't tell if you are joking or doing math while high. I'm OK with that.
Rahz
Well-Known Member
25 par watts per foot is close to maxing out the light intensity. Total wattage depends on the efficiency of the light. If 50% efficient then 50 watts per foot and 800 watts per 4x4, would be similar to a 1000w DE bulb. At 60% efficient the wattage requirement is around 675.
It's possible to go beyond 25 watts per foot which would be around 1300 PPFD. 28-30 watts per foot depending on spectrum will be hitting 1500 PPFD. In theory there should be little yield difference between 1300 and 1500 and both of those levels would see the most benefit using CO2. Without CO2 1200 is probably a more reasonable upper level intensity to shoot for.
It's possible to go beyond 25 watts per foot which would be around 1300 PPFD. 28-30 watts per foot depending on spectrum will be hitting 1500 PPFD. In theory there should be little yield difference between 1300 and 1500 and both of those levels would see the most benefit using CO2. Without CO2 1200 is probably a more reasonable upper level intensity to shoot for.
vostok
Well-Known Member
Profound Bastard
Active Member
You said 157W per square foot is good for early veg, and then told him to double it? High or joking, I still can't tell.
Anywho.
stawawager
Well-Known Member
The light energy dissipates quickly from the Lens to the plant. So if you're colas are five inches from the lenses and thriving, you could have wall-to-wall LEDs except for the incredible ambient heat they would generate. I have 3 300 watt LEDs right now.
Gquebed
Well-Known Member
.
Say.... I have your T4-2100 (x4).... are those 50% efficiency?
Meaning I have 1330 watts there?
Rahz
Well-Known Member
They are 50% efficient at the emitter level. Except for the original Vero lamps I sold which were 45% at the emitter level I've never released anything under 50% output efficiency. The T4-2100 is 300w output so 1200w output for 4 and 600 par watts. Total wattage including fans for 4 should be about 1300 watts but Meanwell drivers often run a bit over current.
Gquebed
Well-Known Member
Exactly what I need to know.
So two of those in a 4x4 is 37.5 watts per square ft.
That's well above the 25w per sq ft that you mentioned in an earlier post which was near maxing out. At 37 w per sq ft am I overdoing it? That could explain some nute probs I had last run...
Gquebed
Well-Known Member
stawawager
Well-Known Member
Good to know that I'm double average wattage. That's how I Roll.
Gquebed
Well-Known Member
Hi...another question...lol
So when COB guys say they are getting a gram per watt or better how are they calculating that? By par watts or by output watts?
Photon Flinger
Well-Known Member
Welcome to the debate.
It's up in the air. Or maybe not. Depends on who you talk to.
If the purpose is to determine operational costs then you probably want to calculate all of your power costs together. Do that for an entire cycle and you can come pretty close to figuring out what your electrical costs will be.
The problem with g/W is that it doesn't take into account the cycle grow time or some other factors which are equally, if not more important. An example would be comparing an indica dominant fast flower done in 75 days versus a sativa finishing up twice as long at 150 but producing twice (or more) weight.
Also consider area which in my opinion is most important. Cramming plants together seems cruel. Let them bush out and fill in to their heart's content. A lot of genetics will state an expected harvest in 1m2 which is just over 10ft2, or 3.3x3.3 roughly, perfect for a nice mid sized plant to flourish.
The 'PED' (performance enhancing drug) equivalent for lighting is going super efficient by running multiple cobs super low at something like 12w each. You want your cobs producing light not heat and the lower they are run, the more efficient they get. You also save on heat sinks since you can use common aluminum sheets at those currents.
Rahz
Well-Known Member
I think I am the only one using grams per par watt
although I've been advocating it for a couple years now. Because there are so many light sources with so many efficiency variances it makes GPW a really bad metric when it comes to defining the theoretical limits of any particular method or strain or skill and also not a very good metric when defining how well a particular spectrum is being used. There will be variances in spectrum and photon count but I'm of the opinion that most warm white spectrums are pretty good. There may be some benefits outside PAR but I don't think it would skew the GPPW figures much. If more IR is useful GPPW would actually favor HPS since the IR is in addition to the par watts and LED wouldn't be getting that boost. HID users should appreciate a par based metric if they want to show how the spectrum is better. If GPPW mentions were common you would see people typically citing numbers in the 2.5-3.5 range across all light types. Try it out on your results and see what you come up with.