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Yes, you're absolutely right. I should have chosen accuracy over brevity. HPS has a huge spike in the orange and red portion of the spectrum with essentially no blue whereas the Mars SP3000R has a huge spike in the red part of the spectrum with essentially no blue. The Mars SP 3000R is...

The best source of info I've seen on VPD is here, on the Pulse Grow website. I used their gear at first but have gone through three complete generations of equipment and am using, and recommend, equipment from AC Infinity. Re. calculating VPD-the Pulse site will give you the background on VPD...

I didn't include it because it would have been a distraction from the point I was trying to make which is that growers have attached a huge amount of mystery to VPD when all it is is one number instead of two. VPD is not an end in itself. It's a number that tells you how much water is leaving...

"penetration" of…? My impression is that marketing people use the term "penetration" to convince readers that light reaches further into the canopy. How that happens is never explained and, so far, I haven't seen any description of what Mars, Vipar, etc. actually mean. In terms of...

I don't know much about your grow but, if you're interested in troubleshooting and were to provide details, something might stand out. Ambient temps in the 60's will definitely reduce growth compared to growing at higher temperatures. At 68°, net photosynthesis is about ½ what it would be at...

"its just my grow it may be unorthodox but ya." - agreed, you have a serious problem in your grow environment. Their growth pattern makes it very clear that they're not getting enough light but the good thing is that you're not spending much money on electricity.

Give it light. 150µmol is for seedlings. By that age, cannabis thrives at 400±µmol. From my current grow:

Thanks for digging that up. Ironically, I did a screenshot of that part of the presentation on "2022-05-01_09-49-10_PM". :-) "An electrically efficient spectrum might grow subpar plants compared to a more broad and balanced spectrum, which is less efficient. Just gotta decide which is more...

"I assumed my high VPD meant the plants were drying out quicker then they can uptake water." - that's all that VPD is. It's the difference between the water pressure in the plant vs the water pressure in the atmosphere. It's physics applied to agriculture. As you're saying, it tells us how...

VPD is the same thing as temperature and RH - it's just one number instead of two. "Once you get dialed in with everything else then start tweeking VPD"- if you get your temperature and RH "dialed" in, those numbers will result in an "optimal" VPD figure because VPD is nothing more that one...

For some time, Bugbee's research was restricted to low THC cannabis but the Federal Government changed licensing and he's been using standard strength cannabis for a few years now. I think it's been a few years but I can't cite a source for that.

"30s and 40s" - I could handle that. I was in KY, GA, and NC when I was in the Army. Winters were pretty mild there. Summers weren't! "I have a light running jacket that feels great but by the time i hit mile 3 Im sweating like a pig." - I hear ya. I bought a "Session" jacket from Tracksmith...

I use Rapid Rooters in a grow dome and I've had excellent results with that approach. My preference would be for RDWC, as is the GrowAce, but not with only a 5 gallon bucket for the plants. RE. the GrowAce - no hands on experience and, after a quick review, the 5 gallons pots are a...

I get that. The full is a big time commitment but even an HM takes up a fair amount of time. I'm a "new runner" so I'm very much in the "building up my endurance" stage. What part of the country (I assume US?) are you in? I'm in Southern California so I can run all year. I ran at 4 PM...

"The growth graphs level out but not flat without extra CO2" Which "growth graph"? The chart below is from the Chandra paper which investigated changes in photosynthesis rates vs temperature and CO2. My hunch is that this is "the science" that the cannabis world glommed on to that leads to...

I've done about half a dozen half marathons with one coming up on 2/3/25. I'm planning on doing my first full marathon on 2/2/26. How about you?

The numbers that you've posted will result in a good yield but I suspect that your plant isn't able to reach its potential at only 550. The only number I've seen for lowest PPFD you want for flower is from "de Bacco University" on You Tube and, IIRC, he puts it at 600µmol. The standard value...

That's an interesting statement. I've seen claims over the years about different approaches but they've all been anecdotes. I've attached the only research I've been able to find on pruning cannabis and, if I understand correctly what you're suggesting, that approach had one of the worst...

I looked into this a while ago and it really depends on who you want to believe. I have not come across any research on this but I did some Googling and came up with the following info. The first bit is copy and paste from the Excel document and then the links are below that...