Have2
Well-Known Member
I have multiple sensors... Some BME280 and 2 from ac infinity controller, I'm testing two controller atm
But I usually put it near the top canopy. Reading seems consistent across the area.
VPD - following chart and south they go!
- Thread starter Have2
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But I usually put it near the top canopy. Reading seems consistent across the area.
ProPheT 216
Well-Known Member
You are changing so many things so fast it's hard to know whats the what in your set up. I think you are over complicating things. Ambient room between 70 and 77 with humidity around 40 to 60 and good light they will grow. I grow all plants on the same feed and in the same environment. I don't change for strains. Find a universal set up.
Have2
Well-Known Member
I usually am around 360-450 ppm. Auto-replenishing nutrients... Ph is stable, ppm too.
I have multiple RH sensors and they all read within few %, which is normal.
Have2
Well-Known Member
Multiple sensors, all reading +/- 4-5%, which is normal. I tested with digital one, bme280, ac infinity. I'll test using the water+salt method and see the numbers.
Hydro setup, water temp at 68° steady. I also tried to play with water temp, it gives a huge difference on leaf temp!
I love this shit, so many things to see/test/change!
Drop That Sound
Well-Known Member
I would set a lawn chair in the middle of the room, right under my hoods, and kick back with my feet up. Chillin' for a good half hour in my undies with my grow shades, and push buttons on all the equipment until the settings feel good..
Have2
Well-Known Member
I'm not changing so many things at once... I love to play around.
As I said, it's only a discussion I wanted to have with others. My results are fantastics, don't worry about this.
I also feed the same shit to all strains. I'm against over dosing and adding 294958392 products.
Thanks for your input!
Have2
Well-Known Member
Ahah I love to do that! So relaxing and a nice feeling when the leaves start to be perky!I would set a lawn chair in the middle of the room, right under my hoods, and kick back with my feet up. Chillin' for a good half hour in my undies with my grow shades, and push buttons on all the equipment until the settings feel good..
Rocket Soul
Well-Known Member
Vpd should not be taken as an end all measurement to chase in itself. Its just how temps and rh compounded in relation eachother, giving you how much water/humidity the air can still take up in absolute terms rather than relative terms (relative would be RH).
But remember when your calculating this youre building in error from several measurements: your thermometer, your rh meter and whatever you use to measure leaf temp. These are three factors that can throw your values off by a lot. So its probably better to tweak your environment until you get the direct plant response, then when you get it you take down temps /rh and calculate VPD and use this as reference for your plants and equipment.
At no time should you treat vpd as something that is more important than the actual visible plant health and general plant posture of your grow. Its more a thing to calculate in which direction to move your temps/rh when you suspect environment being the reason of why your plants are acting poor.
Also remember: apart from the transpiration/vpd: your plants need some baseline temps which is are higher the more intensity you give. Full flower you should go for at least 25C and adapt your rh as needed.
But remember when your calculating this youre building in error from several measurements: your thermometer, your rh meter and whatever you use to measure leaf temp. These are three factors that can throw your values off by a lot. So its probably better to tweak your environment until you get the direct plant response, then when you get it you take down temps /rh and calculate VPD and use this as reference for your plants and equipment.
At no time should you treat vpd as something that is more important than the actual visible plant health and general plant posture of your grow. Its more a thing to calculate in which direction to move your temps/rh when you suspect environment being the reason of why your plants are acting poor.
Also remember: apart from the transpiration/vpd: your plants need some baseline temps which is are higher the more intensity you give. Full flower you should go for at least 25C and adapt your rh as needed.
cannabiscrusader
Well-Known Member
Just read the plants. A light meter is about as useful as a water meter. It doesn't take rocket appliances
I appreciate you response and I need to apologize for the tone of my postings. No excuse.
Re. RH 4± - I switched from a Pulse + Inkbirds to AC Infinity and their humidifier. I calibrated using salt but you can also get a Boveda "kit" which consists of one packet and instructions. The Boveda is quicker and reusable.
Water temp changing leaf temp? I could see that being an impact of having a big bucket of water ameliorating temps but, other than that, the two main factors that would drive LST would be ambient temp, IR radiation (very little from LED's), RH, and wind speed. My grow is in a 2' x 4' tent and the res holds 28 gallons so I know if buffers temps for me. In your setup, would you res have enough thermal mass to impact your plants in that way?
Re. VPD being an issue - what I wrote was describing the problem the wrong way. VPD = a combination of RH, and ambient and leaf surface temperatures. I assume that wind speed is assumed to be 0. Given that VPD is just a proxy for, primarily, ambient temp and RH, if your grow isn't doing well in what is considered an optimal range of VPD values, that has nothing to do with VPD. What it means is that your grow isn't growing in what are considered optimal ranges of temp and RH. That's key — VPD is just a way of expressing two numbers (temp and RH) as one number.
If we take the idea of VPD away, the issue is that your grow is not thriving under RH and temp where cannabis is known to thrive. One question to be asked it "Why?" but another, arguably valid question is, "Who cares?". I'm not being facetious, lemme explain.
Metrics are key to reproducibility, with an underlying assumption that reproducibility is, actually, a goal. Unless you're a stickler for detail, as I am, does it matter that this grow/strain isn't growing under what we humans describe as optimal conditions? The plant's happy and, unless you've got to go to extraordinary lengths to keep the plant healthy, then maybe is just the way this grow/strain functions. I'm not advocating "Lie back and think of England.", if you're familiar with that phrase, but, unless there's a need to "fix" this issue, perhaps it's OK to roll with it.
The "If it ain't broke don't fix it." rule be well applied here. Shift the focus from being on VPD to "is the plant healthy". That grates me, personally, because I'm a process-oriented person (software engineer) but, unless this becomes an ongoing issue, how would "Just let it ride." work for you?
Rocket Soul
Well-Known Member
Agree but will rephrase: shift focus from vpd charts to "at what vpd, as measured by my own equipment, is the plants in my grow happy?" It might be that youre measuring equipment isnt giving you perfect results meaning that the chart only steers you away from the right track, and or that you spectrum/intensity/cultivar simply have different needs or actions on the plant. Generally if you reproduce the VPD of "healthy growth" in your grow environment you will get the same healthy growth the next time. Just remembered that there are separate requirements for temps: you can run the right vpd for 60F for full flower intensity and end up with shitty growth cause the metabolism cant keep up.
Prawn Connery
Well-Known Member
Man, what the fuck did we do back in the days when no-one had ever heard of VPD and we had little way of controlling our environment anyway?
Excellent points. It could be cultivar specific of even just one batch of seeds.
How about this for a "Twins" grow. Two plants from seeds in the same seed packet.
Rocket Soul
Well-Known Member
Grow with lights that had achieved vpd immunityMan, what the fuck did we do back in the days when no-one had ever heard of VPD and we had little way of controlling our environment anyway?
VPD has been around for decades and has been used since soon after people figured it out because it's so important in agriculture.Man, what the fuck did we do back in the days when no-one had ever heard of VPD and we had little way of controlling our environment anyway?
Back in the day, you had fewer growers, more expensive weed (in real terms), and more variable quality.
Must have been!
Everyone knows that temperature and humidity don't matter if you're using HPS!
I heard that the only reason LED's were even invented is that it's a conspiracy to sell VPD machine sensor thingies.
Prawn Connery
Well-Known Member
It was a joke mate. Although it is true a lot of us managed to grow good weed without really thinking about VPD because we read the plant first. If you have to worry about a few degrees or percentages here or there, I'd suggest you have a more direct problem.
Prawn Connery
Well-Known Member
No argument from me.
Take longer to become a good grower? I mean just looking at the plant you (eventually) learned that they look bad when you're sweating like a pig or it is so humid that you can't concentrate. That is using organoleptic tools for environmental measurement.Man, what the fuck did we do back in the days when no-one had ever heard of VPD and we had little way of controlling our environment anyway?
Now you can use some sensors and follow directions in a book. That does not help if you don't know how to collect meaningful data (calibration, proper placement) or ignore your plants. But if you lack that skill you will never learn it.