What are you using? Watts per sq ft

I’m wondering if anyone is getting superior results going above the 40-50 watt per sq foot range I see recommended here.

If heat isn’t an issue, will I get better results with 60 watts per sq ft or would I just be wasting electricity.

I have extra panels I’m not using yet because I only have 2 plants going. I will double my output with the nest batch, but I have the extra lamps and will put them to use if I can expect a better harvest of my current batch - I’ve got 1 that just started flowering and another the same age but hasn’t started yet.

so does anyone have good experiences I can learn from?

The 50 w/sq. ft. value is kind of archaic. Most savvy growers are looking at PAR, PPFD, µmol/m2/second, radiometric footprint, spectrum etc.

For example I’ve been running closer to 25 watts/ but with gucci lights that’s all you need.

PPFD is the value most used: Photosynthetic Photon Flux Density. Remember you have at least two controls on lights: power level (which can be adjusted by height as well as dimmer) and duration. If lights are very high intensity you can shorten the day cycle. Conversely dim lights would increase to get to your daily PPFD. Anything over that and the plant can’t absorb it.

One other area where high intensity is used is with closed-loop CO2 environment. Then you would bump things up another 50% to take advantage of the CO2.

Decent light is where everything starts and all biological functions within the plant are driven by that same light. Low light means low transpiration of nutrients and loose, airy flower.


I think if you do some reading and searches you’ll get the answers you seek. This site is filled with success stories. Search up the strain your growing or lights your talking about and welcoming to the site!

Another question about the same topic.

Obviously not all lights are created equal. 100 watts from a flourescent lamp < 100 watts from a Burple Lamp < 100 watts from high efficiency Samsung diode LED < 100 watts of Sodium (Maybe?)

So there has to be a measurable was of determining of you have enough light, or to determine the quality of the lights you have in your grow room.

I saw a video with someone holding a meter to measure light, it looks like I found one for $21

First of all, does anyone know the scale? This is measuring LUX which is lumens per sq ft. I believe this is the correct measurement to be taking, so if so what is the min, suggested range, and upper bound of effectiveness.

Also, I saw there are apps you can download to measure light - does anyone use one of these apps? is it as good as the device? Can you recommend an app for android?

This forum is fantastic, sorry for all the posts, I’ll settle down after I have the basics down.

How about I tag the light expert @dbrn32 who can help.

LUX meter is really a waste of money. Spend that money on the actual lights. The rule of thumb is to look at the data provided by the manufacturer and will tell you that any light that says something like: “Has the same output as HPS but only draws XXX watts!” is one to stay away from.

Reputable sites like HLG, Spyder Farmer, CHILled Logic, California Lightworks etc will not hesitate to show you why their lights are superior. HLG is pretty much the standard now. I wouldn’t trust much that comes from China.


Thanks, I have 4 different strains I am growing, right now 2 are flowering and another 2 have been planted about 40 days behind. I have autos and I’m going for a 2 plant rotation. Zkittlez and Gorilla Glue are flowering, Bruce Banner and White Widow are trying to pop out of soil.

so I suppose I can vary the intensity by plant if needed by adjusting the height of the lamps, but I think everything has to run with 18/6

Unfortunately, I don’t think anyone has my lights. They are a generic brand using Samsung diodes similar but not the same as HLG or spiderfarm. So, I can’t use someone else’s experience

Thanks, he has helped me already. I guess this is the problem with buying knock-offs.

I’m going to search the documents I got with the lamps, the company doesn’t seem to have a web site and the data on Amazon is limited.

This is the thread where I showed the lights I bought.

I got a total of 1100 watts, 6 150 Watt panels and 2 100 Watt lamps. I planned to return 1 of the 150’s. I have until 1/31/21 to decide if I like the lights and I wanted to have an extra on hand for this grow cycle in case I got a dud. But in all I paid $600 for the 1100 watts, I can return the 6th if none are duds but I imagine for $80 I will just want to keep it in case a panel goes bad before the 50,000 hours of life are over for the rest of the panels. I can probably grow for 20 years with this setup though.

I like many others started out using china lights (blurple). I ended up with 1,320 plug watts before ditching it all and building my own using Samsung EB strips. I now have available a peak of 720 watts (never go over 600 though) and increased yields as a result. My electric bill went down $60 the first month of operation.

Last big grow I did yielded just shy of two pounds (15 grams short) in a 5 1/2 month grow. 1.25 grams per watt is fantastic. Newer lights will do much better than that.

Watts per square foot not a great measure because it doesn’t take into account the Efficacy of light being used. The typical 400 watt hps lamp runs about 1 umol/joule. Some of the higher end led fixtures available right now are capable of running at 3 umol/joule. That is 3x the radiometric energy per watt.


Thanks, I started with Bloomspect Burple lamps, and returned them to upgrade to these. These use a samsung diode, the 301D, where the big brands are using the 301B or 301H.

I am confident these are more efficient than the Bloomspect, but without being able to measure the output, I won’t know what I have until I harvest I guess. I’m trying to optimize my set-up without knowing what my lights actually do and without anyone to reference, so I guess I will err on the side of more light until I know better.

When I bought the lights, I was going to go with 600 Watts for a 6 x 3 growing area. or 4 150 Watt lamps, assuming they would be 25% less efficient than HLG, I was going for a 450 Watt equivalent of 301B or 301H lamps, so I bought 3 instead of 3.

Then when I realized I could get a 350 Watt set-up for under $200 I bought it so I can have a 12 and 12 cycle as well as a 600 Watt 18 hour cycle once I work through all these auto seeds I bought.

The 6th panel is just back-up if I do that, but right now I have auto’s and all these lights so I thought I would spoil them a bit, but not if I’m just throwing electricity away because my plants have all the light they need already.

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I’m going to email the manufacturer and ask what the umol/joule is, is there anything else I want to know that I don’t know to ask?

You could ask for total total radiometric output of light, usually listed as PPF.

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I’ll post the response when I get it.

I have a feeling some dude has 1000 of these sitting his garage after he had them assembled in China. and his name is Joe Kuarez

Check out Dr Bugbee - he knows hemp and light

here is another worth watching. explains the lingo


Are there any meters I can buy to measure what’s going on in my grow room with respect to these values?

sopied from your post…
“Most savvy growers are looking at PAR, PPFD, µmol/m2/second, radiometric footprint, spectrum etc.”

I mean even after I get the manufacturer’s response, it would be useful to be able to measure the results of positioning the lights different ways.

Here is the coverage map in a 2 x 2 grow box for the 1000 Watt version of the Kuarez lamp. It is measured in PPFD, so maybe I can get a clue by comparing to another brand with a 100 Watt lamp.

But based on the values below and your personal knowledge, how does this map look for a 100 Watt lamp?

Asked another and probably better way, what is the desirable range for PPFD? What should be my target for Veg and what should be my target for Flowering?

is 500 a good value? 300?

Thanks for the videos Beardless, I will watch them after the Bears game. I’m watching with my dad, and he’s not cool with weed. Kicked me out of the house 25 years ago for finding an oz in my backpack when I was 17, lol. I moved in with kids from the college in town and partied twice as hard for the rest of high school.

Ppfd average of 600-800 umols per second is what you should be looking for to flower on a 12 hour schedule. In a 2x2 I would look for a ppf of 250-300 umols per second.

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I’m getting pretty lost in my head at this point.

This is the coverage map of the HLG 100 V2 at 12 inches

This is my covverage map, it appears the manufacturer is indicating the KAZ 1000 is approximately equivalent, but I doubt that is true given the price. Is that what you see here, I’m in over my head. I guess the proof will be in my harvest.

Those charts don’t give you ppfd average, is what you would need to calculate dli.

yeah, and they aren’t really comparable charts on top of it - HLG is measuring the outside corners of the boxes and Kuarz who knows, probably the inside corners.

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