AC Infinity lights perplex me. I'm a fan of their products and have been using them for a few years. Their lights are the exception, though.
For you consideration, look at the PPFD map for the Evo
here and for the Spider
here. I've pasted the images themselves below.
The EVO
The standard block size for PPFD maps is 6". I've looked at hundreds of PPFD maps over the past three years and my Spidy senses go off when I see a PPFD map that does not use that grid size. My reason for that it that adhering to a standard makes it easier to compare and not using the standard will tend to obscure detail. In this case, the Evo uses a 9" grid. There's no reason to do that. Using a 6" grid takes a trivial amount of time longer but it provides more detail.
Putting that aside, review the PPFD map for the Evo and disregard the big number in the middle. To the non-discerning eye, having the big number in the center may be seen as a good thing. In fact, it actually ways heavily against the Evo because it demonstrates a very high value in a very small area in the center, surrounded by values that are signficantly lower. which is exactly what you don't want in a cannabis grow light. But I won't hold that against them because the other numbers are what I used to draw my conclusions about AC Infinity lights.
Ideally, a cannabis grow light will provide a very high level of light with no variation in PPFD values from center mass to the edges and corners. Manufacturers can produce a light like that but the price would be very high so they engineer products that give up some uniformity which enables them to hit certain price points.
The Vipar XS-1500 Pro is an example of a small light with high output and excellent uniformity. I was stunned when I saw their PPFD map and they've delivered that product at < $100. It's a very impressive piece of engineering that they've done.
Since I grow in a 2' x 4' tent, I'm more familiar with lights for that form factor and I'm retiring my three year old Growcraft X3 (330 watts) and replacing it with a Spider SE4500 or G4500 (I haven't decided which one). The reason for that is that the Spider PPFD is markedly superior to the Growcraft. Spider has done a good engineering job but it's also a 430 watt light vs the 330 watt light from the Growcraft. I can run a 500 watt driver on my Growcraft and it will churn out a lot more light but it won't be as uniform as the Spider.
Below are the PPFD values from the manfacturers represented by an Excel surface chart.
The hang heights are slightly different but the rates of falloff/attenuation are representative.
These are the PPFD values for the two lights.
The values in the center of the SE4500 are slightly higher than the X3 - 1400µmol vs. 1310. 90µmol is not a huge amount. But you see that as soon as you move off center in the X3, the drop in PPFD is significant. While the X3 is 1300 at the center, it's only 750 in the corner.
I light my grows to a little over 1100µmol at the center which is about a 15% drop from 100% power. When I reduce the dimmer to 85% to get the center value down to 1100, my edge and corner values will drop by about 15%, as well. That takes me from 750 in the corners to 640µmol. No thank you. Due to the drop off of the X3, the plants at the ends of the tend are getting signficantly less light.
Transfer that amount of light falloff to the two lights in question, the Evo and the SF3000. The Evo is very bright in the center but if you raise the light to 18", it's generating 1300µmol and you can't use that much light in ambient CO2. I've been able to grow my photos at 1150µmol and that's higher than most growers will try to go. 1000µmol is a much safer level of light in ambient CO2.
For simplicity sake, let's look at the 12" PPFD map for the EVO. When you dial your Evo down to 1000µmol, on the edges your PPFD will drop by roughly 27% and 42% around the edges. That's 2.25 sq ft of even light and then a huge drop off.
Now switch to the Spider. At 10", you have 4 sq feet of grow area that is receiving the same amount of light. That 4 square feet is 44% larger than the 2.25 square feet that you get with the AC Infinity. And, in reality, the light cast is even better than that because th 9" grid square that AC Infinity is using will tend to produce higher values than if they were using a 6" grid square.
All other things being equal, it's much easier to light a grow with uniform levels of light with the Spider than it is with the Evo. The Evo looks brighter to the human eye but the human eye has a very limited ability to gauge brightness and it can't be seriously argued that we can see differences in PPFD values across a grow tent.
Another fun fact and this was a blinding flash of the obvious for me — I top and LST my plants (ref the attached picture) so that there's not a lot of foliage in the center of the plant. In fact, my well trained plants are "hollow" in the center, with the branches splaying out to the edge of the tent and then growing vertical. And where is the light is the brightest — in the center of the tent! Oops…
Yes, the Evo may look brighter and there's that big number in the center but when you look at the amount of PAR that is being generated and where it's being generated, I think there's a strong case that the Spider generates a light pattern that, all other things being equal, will result in a higher yielding crop.
