# Watts per Square Foot Question

How much of a difference, if there is a noticeable difference between -

quality of bud/quantity of bud versus watts per square foot in a grow tent?

Mainly 50 watts/f2 vs. 37.5 watts/f2…

These watts are measured at socket and are Sonofarm SF4000.

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You really should determine the light size. By using PPFD to measure the light output, and using the size of the grow area. There are some calculators on HLG’s website, that you can plug your numbers into.
If you just go with a rule of thumb. I would recommend that you start with the 37 watts per square foot. I was running 320 watts in a 2x3, (53 watts),and couldn’t turn it up more than 50%.

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Why couldn’t yoi turn it up to full power?

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It has more to do with the efficiency of the light, and less to do with the watts. You are better off with 35 watts per square foot at an efficiency of 2.8, than 50 watts at 2.0.
@dbrn32, knows more about this than me, and I am sure he can explain it better.

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How is the dimmer on your SF4000? The dimmer on my SF4000 is very inaccurate and I use a Kill-A-Watt meter to set it. Also what is the top draw on yours. Just curious. Mine topped out right at 400.

What size space in the light covering?

Exactly! Not every light produces the same amount of light per watt, so watts per ft² not a great indicator of what your plants will respond the best to.

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Thanks.

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HLG 350R, 340 watts max and dimmer dial used with LUX meter for setting power level Under 50% at 20-25inches above (50,000LUX) Vipar Spectra V1200 same LUX reading for same height, 535watts, but twice the foot-print of the HLG. HLG \$550 and Vipar Spectra V1200 \$300 or something like that.
48x48x80 tent.

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My 350R would roast my plants at full power even if it was hung at the top of my 2x4. I usually end up at 70% in flower. That gets mid 40s DLI across the canopy. There’s less strain on the LEDs at 70% than 100% and should lengthen the life of the light.

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I can tell you my yields went up about 30% when I went from 200W to 400W in my 3x3.

Good luck and you are in good hands with these fine people.

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@beardless I have 4 and looking at getting one/two more. I want to run 3 or 4 in my 4x8x80 and 2 in my 4x4x80.
I will have to look my draw when I get home. I’ve always use 395 across the board for any of them as this is what wattage measured out to average when I first measured them all…

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Thanks everyone for your help. I’ve have been reading and learning since I asked my question. I have a better understanding of PAR, DLI, etc… Gonna see if I can download on this phone and get readings. Also have some equations using LUX to get other readings.

Thanks again.

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Adding HLG-30 UVA bar for residence in my tent, in route.

My android app maxed at 32,000. my light meter goes double, minimum.

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You’re gonna like the UVA.

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