Hello all, first post here. Some intro….I decided to set up a DWC lettuce/spinach grow as practice for weed once it became legal, so I built a 2’ X 4’ X 4.5’ grow box out of scrap wood. The greens take up most of the footprint, but I left a 2’ X 1.3’ space at one end for weed. I went with CFLs because the greens don’t need much light, and I didn’t know if I would be successful or motivated to continue, so I didn’t want to invest in a store bought grow light.
Once the weed end was set up, I used 8 X 23W CFLs (184W, 4 sockets, 4 two way splitters) for veg on one bank, and for flowering I set up another bank with a mix of CFLs and screw in 15W LEDs (globes off). I am using DWC in a 10 gallon reservoir with 4 spots. This is crowded, but to give more room, I set up a 2’ x 2’ scrog net and directed the plants over to the side of the reservoir, over top of the lettuce/spinach setup. So I need to light 2.6 ft2 for early veg, and 4 ft2 for late veg and flower.
This setup worked for 3 grows, but I was using over 300W for flowering, and generating quite a bit of heat. The screw in LEDs put out the light, but they were more of a spotlight than the overall light of the CFLs, so at close range they didn’t provide much coverage and were too strong.
So I read up on SILs, including posts by @Olderfart, and decided to ditch the CFLs. I modified one of my banks to have 8 sockets, and put in 8 15W SILs. These are 3000K and 1600 lumens, mostly Feit brand. First impression – wow, is that ever bright!!
According to cocoforcannabis.com, the recommendation is for 65 useable PPF per square foot. My main area is 2’ x 1.3’ = 2.6 square feet, so I was looking to target 169 useable PPF for lighting. From the calculator at https://www.waveformlighting.com/horticulture/convert-lumens-to-ppf-online-calculator , and using Olderfart’s 20% increase in lumens by taking the globes off, I see that my 8 SILs should put out 269 umol/sec (average of high CRI and low CRI values for 3000K LED), which is equivalent to 197 useable PPF). So there is some light to spare.
I decided to run some tests with a light meter app. After looking at a few, I settled on Korona. No one thinks that a free app can replace a proper meter, but at least Korona has done some testing against real meters, which is available on their website.
So first I tested my 8 x 23W CFLs for a baseline. This figure shows what the app gave me for lux and PAR. Dimensions in the figure are in cm. I ran the test at a 22 cm distance. No one runs their CFLs that far away, but it’s too hard to read the results on the phone with the lights at 5 cm like I run them.
Then I tested my 8 x 15W SILs. I did one test at 22 cm distance for a direct comparison. As expected, the SILs were WAY brighter than the CFLs.
I also did some limited testing of the LED setup at 15 cm distance, 30, and 50.
So are the numbers accurate? Hard to say. I sent the test results to Korona, the app developer, and their opinion was that the numbers were in the ballpark for 120 rated Watts of these bulbs.
Whether my test numbers are accurate or not, I have answered my three main questions:
-is my 8 LED setup brighter than my 8 CFL? YES, A LOT!
-is there good light distribution over the whole space? YES
-have I decreased the power consumption and heat? YES
The plants will have the final say…..
Safety wise, I put 5 minute epoxy on the two exposed contacts on each bulb. Although it's easy to pry off the whole plastic globe, I like the ones that I cut off because there is a rim of plastic that helps you avoid accidental contact with the contacts and LEDs. The whole setup is on a GFCI outlet.
Once the weed end was set up, I used 8 X 23W CFLs (184W, 4 sockets, 4 two way splitters) for veg on one bank, and for flowering I set up another bank with a mix of CFLs and screw in 15W LEDs (globes off). I am using DWC in a 10 gallon reservoir with 4 spots. This is crowded, but to give more room, I set up a 2’ x 2’ scrog net and directed the plants over to the side of the reservoir, over top of the lettuce/spinach setup. So I need to light 2.6 ft2 for early veg, and 4 ft2 for late veg and flower.
This setup worked for 3 grows, but I was using over 300W for flowering, and generating quite a bit of heat. The screw in LEDs put out the light, but they were more of a spotlight than the overall light of the CFLs, so at close range they didn’t provide much coverage and were too strong.
So I read up on SILs, including posts by @Olderfart, and decided to ditch the CFLs. I modified one of my banks to have 8 sockets, and put in 8 15W SILs. These are 3000K and 1600 lumens, mostly Feit brand. First impression – wow, is that ever bright!!
According to cocoforcannabis.com, the recommendation is for 65 useable PPF per square foot. My main area is 2’ x 1.3’ = 2.6 square feet, so I was looking to target 169 useable PPF for lighting. From the calculator at https://www.waveformlighting.com/horticulture/convert-lumens-to-ppf-online-calculator , and using Olderfart’s 20% increase in lumens by taking the globes off, I see that my 8 SILs should put out 269 umol/sec (average of high CRI and low CRI values for 3000K LED), which is equivalent to 197 useable PPF). So there is some light to spare.
I decided to run some tests with a light meter app. After looking at a few, I settled on Korona. No one thinks that a free app can replace a proper meter, but at least Korona has done some testing against real meters, which is available on their website.
So first I tested my 8 x 23W CFLs for a baseline. This figure shows what the app gave me for lux and PAR. Dimensions in the figure are in cm. I ran the test at a 22 cm distance. No one runs their CFLs that far away, but it’s too hard to read the results on the phone with the lights at 5 cm like I run them.
Then I tested my 8 x 15W SILs. I did one test at 22 cm distance for a direct comparison. As expected, the SILs were WAY brighter than the CFLs.
I also did some limited testing of the LED setup at 15 cm distance, 30, and 50.
So are the numbers accurate? Hard to say. I sent the test results to Korona, the app developer, and their opinion was that the numbers were in the ballpark for 120 rated Watts of these bulbs.
Whether my test numbers are accurate or not, I have answered my three main questions:
-is my 8 LED setup brighter than my 8 CFL? YES, A LOT!
-is there good light distribution over the whole space? YES
-have I decreased the power consumption and heat? YES
The plants will have the final say…..
Safety wise, I put 5 minute epoxy on the two exposed contacts on each bulb. Although it's easy to pry off the whole plastic globe, I like the ones that I cut off because there is a rim of plastic that helps you avoid accidental contact with the contacts and LEDs. The whole setup is on a GFCI outlet.
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. I didn't find the bulbs on super sale like some; paid $3.40 each.
