Chat
Recommended

Which Light to use

BearBuds
BearBudsstarted grow question 2h ago
Hello Grow Diaries! I have a question about lighting. I have this brand new HLG 200 RSpec light and my plan was to use it for flowering. I also have an older HLG 320R QB that I could use. Would it be better to use to 200 at full power or the 320 at ~75% power?
Open
Week 5
likes
Answer
00110001001001111O
00110001001001111Oanswered grow question 1h ago
you need to compare apples to apples using umol/s PAR production, not watts. efficacy x watts = umol/s PAR. use those numbers to determing the percentage of power to make them equivalent as far as light production. The frame with better diode distribution will be your best option. You could run both of them at lower levels, too... improve light distirbution, potentially, but some drivers lose efficiency below ~50% .. depends on the model in front of you. for 12 houroperation you want 80umol/s per sq ft -- that puts you near 37 DLI. 37 dli over 18hours is 2/3rds of that.. which is 53 1/3 umol/s per sq ft. Easy math from there... 80 x sq ft of tent = the amount of PAR produced from a light that you need for that tent. if one light produces enough, then it is enough. or, use both and a little more math to determing the pecent power to run both whil producing the calculated amount of PAR required for the tent. This "37" DLI is a good starting point for ambient CO2 levels. You will need to make small adjustments from there based on plant growth. There is no 1 answer for all in this regard as more than one factor adds up to what the maximum amount of light a plant can handle per day.
likes
Complain
m0use
m0useanswered grow question 2h ago
You will want to compare a few things first. Its DLI, whatever one gets you a good DLI of around 35-40 and even lighting "less hot/cold spots" is best. then its spectrum, If its got some reds in it vs just blue they that would be ideal, but its not 100% needed, most lights are well rounded in the last decade or so that use white led's. then its efficiency for hydro cost. They likely so close it does not matter TBH but its more a thing for different types of like lke HID vs LED vs CFL. Best to find the PPFD maps "manufactures site" for each light and do some ruff math on the DLI. you can google PPFD to DLI and it will show you how to calculate that. Even if you hit a DLI of lets says 37, and the plants are getting stunted it just means they may want a bit less intensity on that. different strains have different needs but the upper limit with no added CO2 is about 40DLI, this was calculated by dr.brucebugbee a cannabis researcher. He has a lot of good videos on youtube if you wanna watch em. Go from there, I'm sure both lights can do the job just fine but finding the hangheight, dim setting and schedule for it will need a bit of work.
1 like
Complain