I'm Second Guessing my Lighting

Hello all,

This is my first grow in almost ten years. I have set up an extra ~7’x6’ room in my basement as a grow room. I currently have 11 autoflower plants a week or so into flowering. It’s a little tight in there, I know, but at this point that is not my concern. Where I am concerned is with my lighting choices. From the start I was using 1 2000w (“equivalent”) King Plus LED light (https://www.amazon.com/Double-Spectrum-Greenhouse-Flowering-Growing/dp/B01MY27Q9H/ref=cm_cr_arp_d_product_top?ie=UTF8). It seemed to be working great at the plants grew strong and fast. A couple of days ago I added an additional King Plus 1000w LED lamp (https://www.amazon.com/gp/product/B0185OLBPK/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1). I was hoping to add an additional 1000w LED of the same brand, but found myself doing some research on LED grow lights in general. Needless to say, I now feel like I am way under-lit.

I came across the general rule, on this site and a few others, that you want at least 32 actual watts per sq/ft. That means that I would need 7x6x32 = 1344 actual watts for the garden. The 2000"w" lamp actually draws 380 watts and the 1000"w" actually draws ~190. This puts me at 570 actual watts.

Now my question is, I guess not a single question at all. Is this general rule true? I have read it can very much depend on the build and quality of the light itself.

If I am under-lit what is the option that I should pursue to make up for the short coming? I can add 3 more 1000w lamps to bring my total wattage to 1,140. Or. . . ?

Other that solving the low light problem, my main concern is electricity usage. But, wouldn’t electricity use be the same if you had, for example 1 1000w HPS/MH lamp vs multiple LED lamps with an actual wattage draw of 1000 watts? I guess I am overall confused as to why, if you are not worried about heat, you would opt for an LED lamp if the equivalent wattage is useless and it is the actual wattage that counts.

If anyone out there has specific lamps they would suggest or has had luck with the King LEDs, I would love to hear from you. Also any tips or general direction would be greatly appreciated. Thanks in advance!


@dbrn32 will be along shortly, class will be in session once he responds


Looking forward to it. Thanks!


Here are some specs from the King LED owner manual.


These are pretty decent lights and should serve you well enough for the price you paid.
Uses 10W LED Epistar chips.

The GLARING problem for me was the manufacturers claim about coverage!

True coverage areas for your lights are:
2000W will cover a 4 X 4 area
1000W will cover a 3 X 3 area

Not too sure their PAR and Lumen ratings are accurate though.

If you check on YouTube, there are some reviews of your lights.

Interested to hear everyone else’s thoughts!


Hi @gourmetbouquet

I worked on my grow calculations today (geeked out actually) and what I found for wattage per square foot for flowering is as follows:

  • 30 minimum
  • 50+ optimal
    This does not factor in how even your coverage is based on the manufacturers preferred footprint.

I can tell you @dbrn32 is an absolute master at lighting. I should have listened about how good the QB boards are in the beginning and not bought a Roleandro 600 watt blurple. It works, but that money would have been much better spent toward the QB products. I am by no means an expert…just trying to help a wee bit.


The “35-50 watts per square foot” rule is really for HID lighting (and perhaps debatable, but still good enough to go by).
When it comes to LED lighting, it’s all about PPF and umols/second - which I’ve learned by reading everything @dbrn32 posts, so I won’t say another thing about it!


@dbrn32 has sold a lot of these. I hope HLG are monitoring this site and sends a commission check.


I agree with @gourmetbouquet wish I would of started off with the QB’s live and learn good luck on your grow this stuff is amazing sorry just medicated lol


My DIY 4xQB304 @450W puts out 80,000 lumens. Its not just watts at the wall but the efficiency of the leds as well. Most burples waste electric on heat.


With LEDs more smaller (3x300) is better than one 900. You can make your foot print bigger


Welcome to the forum @gourmetbouquet!

To answer your question about power, watts are watts. At least by electrical theory and the formula for watts being volts x amps. The fuzzy math comes in when you start trying to figure out how effective each fixture is at producing light. There is no standard, or rule of thumb that applies across the board. Even if you just narrowed field to leds, there are some really good and a lot of not so good.

What you’re looking for out of a light is to meet daily light integral on flowering light schedule. To do this, you’re looking at photosynthetic photon flux density average of between 500 and 800 umols per second. That’s fancy way of saying total radiometric light energy over area in square meters. Your 7’x6’ room is about 4m². So to hit a ppfd average of 500, you’d need a light or combination of lights totaling a ppf of 2000 umols per second. And remember, that’s to hit minimum suggested levels on a 12 hour light schedule.

From there, you just need a light that gives you total flux or to guess at what the total flux is. Your king fixtures probably run about 1.2-1.4 ppf per watt per second. So whatever the actual power consumption is, give them the benefit of doubt and multiply it by 1.4. Nobody shells out the cash to test all of those lights in integrated sphere, so it’s about the best we can do. Running reverse math on them is how people come up with numbers like “50 watts per square foot”. The truth is, some lights are better at 30 watts per square foot than others are at 50 watts per square foot. To get into those better lights, you should expect to pay a little more. But we can knock them down assembling kits or building ourselves too.


Wow! Thanks for taking the time to write that up. I’ll be honest, it’s got my head spinning, but I’ll take my time trying to figure out what it all means.


@dbrn32 & @WickedAle.

Im trying to research as much as possible on lights and I’m loving the 3 different QB set ups I am using. But i too am still not sure about all the terminology and ratings.

Assuming that a DIY QB set up is the call, what would you suggest for @gourmetbouquet ‘s grow room needs?

When in doubt, put it in the pros hands!


I feel a lot more comfortable about standing behind a recommendation for ppfd average being in 700-800 range. In that space, a total ppf of 2800-3200 umols per second. A v2 288 board at what I’ll call standard operating range is worth about 300 umols per second. So like 10ish boards, however you get there.

May be worth looking into doing something with a series of 120/132 boards. Cost vs coverage there may work out to be a little cheaper. Those are full DIY builds though, if that matters.


@gourmetbouquet, I built a 2x288 board. Super easy.

If you are serious about your grow, don’t skimp on lights.

My 2x288-


I use ChilLogic lights from Rapid Led. They grow good weed and right now I’ve got them dimmed to 600 watts in a 4x4 area. They also cost me about $1 a watt. I can’t build a light any cheaper myself. I know QBs are very efficient and a lot of people are using them, but I’m very impressed with these lights.




I too am a big fan of Rapid LED kits. I have a combination of Chilled Logic pucks and Bridgelux VERO 29 COB’s (plus red/far red and UV supplements).

The folks a Rapid LED are very responsive and helpful if you have questions.


An additional note regarding Rapid LED, my current lighting was put together over a six month period and each of the five orders were customized orders. The folks at Rapid LED handled the customizations with no problem. In one case I had incorrectly specified a component which they caught and contacted me before filling the order.

Excellent support.


I also enjoy my Rapid LED kit with upgraded drivers, and the CREE CXB3590 90CRI.
I can run them at 817 watts total if I wanted. The staff is phenomenal, I would would order again in a second from them.