Question on cross lighting

Are 4 100w lights equal to a single 400w light??? Or does cross lighting improve the 4 single lights???
Just curious really

Can’t answer the question. LUX, PPFD, PAR, and DLI are terms all are involved. To answer your question, with any accuracy, a light meter-sensor-measuring device. n two weeks, I will be better equiped and may be able to answer your question. My android phone app maxes out at 33,000 lux.
Not close to quality, as reported by forum users. I bought these today. Time to get off the LIGHT fence.

There’s 2 answers to your question. The simple is yes, the more diffuse your lighting is better. When it hits your canopy from more directions there is greater canopy penetration and more balanced intensity across the canopy.

The more complicated answer depends on which lights and how efficient they are. If you have a 400 watt light that runs at 3 umol/joule the total ppf is 1200 umols/s. 4-100 watt lights that run at 2 umol/joule would have a total ppf of 800 umols/s. In this scenario the 400 watt light would have 33% higher light output. Depending on size of your space the single 400 watt light could perform better because your light density would be higher. The only consideration “watts” or power consumed have anymore is how much a particular may cost to run. Lighting technology is all over the place right now, so comparing power consumption is nearly useless in comparison to 40 years ago when hid lights were only way to go and they all had roughly the same performance.


@dbrn32, thanks for your last reply! I just got a 5x5 tent, and want to use my existing 350R and 260 Rspec in it, this is a total of 590 watts. This is 24 watts per square foot. I was worried that this was not enough, and was thinking more along the lines of 40 watts per square foot. I finally emailed HTG with the question of is this enough light? They replied that the two lights will be a great choice for a 5x5.
After this experience, and reading your last reply I think we need a better way to figure watts per square foot. What do you think this simple formula?
Start with a base of 35 watts per square foot at an efficiency of 2.5, and then use a multiplier on the efficiency to reset the total. Something like this, I know the numbers will need to be tweaked.
35 watts at 2.0 efficiency is x 1.2 equals 42 watts per square foot
35 watts at 2.3 efficiency is x 1.1 equals 38.5 watts per square foot
35 watts at 2.5 efficiency is x 1.0 equals 35 watts per square foot
35 watts at 2.7 efficiency is x .9 equals 31.5 watts per square foot
35 watts at 2.8 efficiency is x .8 equals 28 watts per square foot

Imo watts are irrelevant, use ppf per m². That is what hlg uses to determine and display a recommended canopy size for each light.

1 Like