Great that YT is laying my videos in your path, Alan! Appreciate the positivity.

Heheh! Thanks, I appreciate your concern. Yes, a few upgrades ahead of these now. :)

When using a nutrient doser, I go for a 2:1 dilution (two parts RO water, one part acid) although I know some growers who don’t dilute at all due to the small amounts added each time. I like to be on the safe side and it gives me a finer granularity of adjustment with my small reservoir.

@Just4Growers Thank you for the reply good sir 👍

@@hannibalb893 Always happy to help if I can.

You're absolutely right- HEPA filters are made for removing pollen and mold spores.

@Just4Growers My point being that carbon filters are not meant for that, nor should they be used for that.

Thanks for underlining the point! I've cut out the misinformation at 9 - 12 seconds. Appreciate your input!

Thanks for watching! Appreciate your support :) ❤

Hi there @Grrrnthumb and thanks for taking the time to chime in! I have to take issue with your claim that vapor pressure deficit (VPD) is "identical to absolute humidity (AH)" though as this is demonstrably inaccurate and might well reflect a misunderstanding of the physics behind these concepts. Let me try to clarify: *VPD vs. Absolute Humidity: Distinct Concepts* Absolute Humidity (AH): Refers to the mass of water vapor present in a unit volume of air, typically expressed in grams per cubic meter (g/m³). It provides a measure of how much water vapor is in the air but does not account for temperature or the air's capacity to hold moisture. Vapor Pressure Deficit (VPD): Represents the difference between the current water vapor pressure in the air and the maximum water vapor pressure the air could hold at the same temperature (saturation vapor pressure). It is expressed in units of pressure, such as kilopascals (kPa). VPD inherently integrates both temperature and humidity, making it a more dynamic and physiologically relevant metric for plant water relations. Key Difference: While AH measures water vapor content only, VPD quantifies the drying power of air on plant surfaces, directly influencing transpiration rates and stomatal behavior. *VPD is Not 'Just Another Scale'* The analogy to Celsius and Fahrenheit is flawed because AH and VPD measure fundamentally different properties: Celsius and Fahrenheit measure the same phenomenon (temperature) on different scales. VPD and AH, however, do not measure the same phenomenon. VPD incorporates temperature-driven changes in saturation vapor pressure, which AH does not address. Example: At the same absolute humidity, air at 25°C will have a significantly lower VPD than air at 35°C because the saturation vapor pressure increases exponentially with temperature. This is critical for plant physiology, as plants respond to the relative drying potential of the air (VPD), not just the amount of water vapor present. *Physiological Relevance of VPD* VPD is highly relevant to plant well-being because it directly affects: Transpiration Rates: VPD drives water loss through stomata. Low VPD can suppress transpiration and lead to stomatal closure, reducing carbon dioxide intake and slowing photosynthesis. High VPD can lead to excessive water loss and plant stress. Stomatal Conductance: Plants regulate stomatal opening based on the drying power of the air, which is captured by VPD rather than AH or relative humidity. Water Use Efficiency (WUE): Optimal VPD ensures efficient water usage while maximizing photosynthetic activity. Absolute humidity, on the other hand, does not account for how temperature influences these processes, making it a poor standalone metric for cultivators. *Historical and Practical Use of VPD* Your suggestion that VPD is "merely jargon" is also incorrect. VPD is widely studied and used in agronomy, horticulture, and plant physiology because it correlates strongly with plant water relations and stress responses. Your claim that VPD is a modern invention "to impress" is ...unimpressive. :) The concept has been used in scientific literature for decades and is well-supported by empirical research. Studies show that managing VPD within optimal ranges can improve crop growth, reduce disease susceptibility, and enhance overall yield. Examples include controlled environment agriculture research on crops like tomatoes, cannabis, and lettuce. *Why Relative Humidity is Insufficient Alone* Relative humidity (RH) varies with temperature and does not directly convey the drying power of air. For example: Air at 80% RH and 20°C has a lower VPD (less drying power) than air at 80% RH and 30°C, even though the RH value is identical. RH fails to capture the interplay between temperature, air moisture capacity, and plant physiology, which VPD does by design. VPD is not identical to absolute humidity, nor is it redundant jargon. It is a scientifically robust metric that integrates temperature and humidity to describe the air's capacity to drive transpiration and impact plant water relations. While absolute humidity and relative humidity have their uses, neither is as physiologically relevant to plants as VPD. So, amigo, I'd definitely suggest showing more trepidation and, dare I say, humility before embarking on a wholesale dismissal of VPD as "a joke" and, instead, take some time to explore the term's scientific foundation and practical applications in modern horticulture and plant science. For further reading, check out the undergrad textbook: "Plant Physiology" by Taiz, L., & Zeiger, E. Happy growing!

​@@Just4Growers Oh boy, you're in for quite a surprise, lol. I can agree there is a misunderstanding of the physics here from one of us. Yes I read a few hundred studies a year and I know exactly how often VPD is used in the literature and how. We can definitely see a pervasive excess of overall unnecessary jargon increase in papers using VPD. It's an unfortunate pattern. There is one way to definitely decide this issue. If I'm right, then every single exact VPD amount should have 1 and only 1 single possible AH value. Also, every AH value should have only 1 possible corresponding VPD value. That's hard factual proof. Now just go see if that is true (hint: it is). Then come back and admit who completely misunderstood the physics.

​@@Grrrnthumb You're right ... one of us is in store for quite a surprise, lol. And you’re also correct that this boils down to understanding the physics-and one of us indeed misunderstands it. We agree on all of that. But now, let's both take a deep breath and follow your logic step by step and settle this once and for all with verifiable calculations. You claim that "every single exact VPD amount should have one and only one corresponding AH value" and vice versa. If true, this would indeed prove your point. However, I can demonstrate that this is not true because both VPD and AH are temperature-dependent, and temperature fundamentally changes the relationship between these two variables. Allow me to underline my argument using some examples: Formulas Used: AH = (1000 × AVP) / [0.4615 × (T + 273.15)] *Case 1: Same VPD, Different AH* VPD = 1.0 kPa *Temp = 20°C* AH = (1000 × 1.338) / [0.4615 × (20 + 273.15)] AH = 1338 / [0.4615 × 293.15] AH = 1338 / 135.344 AH ≈ 9.89 g/m³ *Temp = 30°C* AH = (1000 × 3.243) / [0.4615 × (30 + 273.15)] AH = 3243 / [0.4615 × 303.15] AH = 3243 / 139.977 AH ≈ 23.17 g/m³ At 20°C: AH ≈ 9.89 g/m³ At 30°C: AH ≈ 23.17 g/m³ *Result: Despite having the same VPD of 1.0 kPa, the AH values are significantly different due to the temperature difference.* *Case 2: Same AH, Different VPD* Formulas Used: Actual Vapor Pressure (AVP): AVP = (AH × (T + 273.15)) / 2167 AH: Absolute Humidity in grams per cubic meter (g/m³) T: Temperature in degrees Celsius (°C) AVP: Actual Vapor Pressure in kilopascals (kPa) Saturation Vapor Pressure (SVP): SVP = 0.6108 × exp[(17.27 × T) / (T + 237.3)] SVP: Saturation Vapor Pressure in kilopascals (kPa) exp: Exponential function Vapor Pressure Deficit (VPD): VPD = SVP - AVP Scenario at 15°C Given: Temperature (T): 15°C Absolute Humidity (AH): 8 g/m³ Calculations: Calculate AVP: AVP = (8 × (15 + 273.15)) / 2167 AVP = (8 × 288.15) / 2167 AVP = 2305.2 / 2167 AVP ≈ 1.064 kPa Calculate SVP: Calculate the exponent: Exponent = (17.27 × 15) / (15 + 237.3) Exponent = (259.05) / 252.3 Exponent ≈ 1.026 Calculate SVP: SVP = 0.6108 × exp(1.026) SVP ≈ 0.6108 × 2.790 SVP ≈ 1.705 kPa Calculate VPD: VPD = SVP - AVP VPD = 1.705 - 1.064 VPD ≈ 0.641 kPa Scenario at 25°C Given: Temperature (T): 25°C Absolute Humidity (AH): 8 g/m³ Calculations: Calculate AVP: AVP = (8 × (25 + 273.15)) / 2167 AVP = (8 × 298.15) / 2167 AVP = 2385.2 / 2167 AVP ≈ 1.101 kPa Calculate SVP: Exponent = (17.27 × 25) / (25 + 237.3) Exponent = (431.75) / 262.3 Exponent ≈ 1.646 Calculate SVP: SVP = 0.6108 × exp(1.646) SVP ≈ 0.6108 × 5.186 SVP ≈ 3.169 kPa Calculate VPD: VPD = SVP - AVP VPD = 3.169 - 1.101 VPD ≈ 2.068 kPa *Results:* At 15°C: AVP ≈ 1.064 kPa SVP ≈ 1.705 kPa VPD ≈ 0.641 kPa At 25°C: AVP ≈ 1.101 kPa SVP ≈ 3.169 kPa VPD ≈ 2.068 kPa *Despite having the same Absolute Humidity of 8 g/m³, the VPD values are different at different temperatures:* At 15°C, VPD ≈ 0.641 kPa At 25°C, VPD ≈ 2.068 kPa This demonstrates that the same AH can *indeed* correspond to different VPD values when temperature changes, supporting my argument that there's no one-to-one relationship between VPD and AH across different temperatures. Thus, your purported “one-to-one” relationship between VPD and AH simply doesn’t hold up when you account for temperature, which changes the saturation vapor pressure of air. VPD measures the air’s drying power, which plants respond to physiologically. AH is simply the water vapor content of air, a static measure with no direct indication of how much more water the air can hold or how it interacts with plant surfaces. You’re right that jargon should serve a purpose-and VPD does. It dynamically integrates temperature and humidity to guide plant management in ways AH cannot. Misunderstanding this relationship leads to flawed conclusions about VPD’s validity. Thanks for the challenge; it’s a great opportunity to clear up these misconceptions. And hopefully, this clears up who misunderstood the physics here! :)

​@@Just4Growers Yes, I agree the calculations should be verifiable. So to do that, instead of drawn out math discussion using the most complicated way to find VPD, we can use the many online calculators to verify, they all give the same results if we use the same inputs. They agree we only need input a fixed RH & fixed temp to get a fixed VPD. Do you agree with them? Btw, I won't be available for a couple days, but I will be back!

@Grrrnthumb Rather than invoking any third parties, I think we should stick to the pure math and physics of VPD. The calculations I provided are not complicated, so please take as long as you want to review the examples I provided and let me know if you agree or disagree with my reasoning. Always happy to help and discuss amigo. Sending best wishes to you and your garden. PEACE ❤

Hi there! Thanks so much for your sub and kind words. So-are you filtering the air in your home's living quarters or grow room? Grow rooms are typically a lot more demanding than living quarters. This is evinced by the fact that growers tend to talk in terms of air exchanges per minute whereas for domestic air purification, it's air exchanges per hour. Nevertheless, for general air purification, aim for 4 to 6 air exchanges per hour, or 0.07 - 0.1 air exchanges per minute. If you live with smokers or want to step up the purification a little, aim for 8 - 12 ACH or 0.13 - 0.2 air exchanges per minute. For example, for a room with a volume of 5000 cubic feet, you'd want an extraction fan rated for around 500 CFM - for high level purification, go for 800 to 1000 CFM. For this example, an 8" diameter inline fan would be sufficient.

​@@Just4GrowersThank you for your valuable information. I'll start with an 8" carbon filter, so I'll be able to tell the difference in air quality from room to room. I was looking to clean the air in my home, I was trying to be funny, but it's true when I said it would be great if I could set up my home with grow room ventilation. I'm sure the filtered air would be amazing. I'm subscribed and I'll keep enjoying your videos. Thank you 😄

Lint-free is fine.

Sorry about that. I’ve cut back on caffeine.

The solutes in a nutrient solution are totally dissolved in water so won’t be subject to filtration or additional dilution due to passing through the fabric pots.

@@Just4Growers Thanks for all the great info over the years. I've been watching for close to a decade

Sorry about that! Try adjusting the playback speed to x 0.75

Yes- what species and size?

I appreciate that Tom! Thanks :)

@Just4Growers Ok! Your April fool's video planning: ideas Miracle grow Plant whisper A Pet Rock for your plants Choosing music for your plants personality A growable T-shirt, to sell merch 👕 😂 A Talking plant Instant plant growth spray Plants that can create electricity 💡

I’ll pop some block covers on next time and try to take it easier with my irrigation. “By their fruits you will know them.” :)

I’d recommend a 70/30 coco/perlite mix for that watering frequency.

@@Just4Growers I have a bag of it right here I haven't found it necessary I like to use it for cuttings

Okay, okay. Would you like a more chill update to this video? I’d be happy to make it. :) In any case, thanks for the feedback!

​@Just4Growers im not a nativ spreaker and with increasing speed its hard to follow. Thats what i wanted to say. The first half was ok. The infos you provide in this video are good and important. And the style is good too. Its just the increasing speed Found your vid in a cannabis forum, was exactly what i was searching for.

Thanks for your support as always Mohsen!

Hi TvToms, firstly THANKS for your questions and sorry for the delay in getting back to you. I wanted to perform a few checks first. Short answer: No. While the OnePen is great for submerging in nutrient solution while you’re mixing up and making adjustments (great to have both hands free for that!) it will disconnect from the app after a few minutes of inactivity - probably to conserve battery life. So, it’s good for hands free testing while you’re mixing up, or taking measurements at set intervals as you say, but if you want a continuous monitor I suggest going with the Bluelab Guardian Connect.

@@Just4Growers Sounds OK. It is nice to just glance over and see the numbers on a widget or something, but not required. I can still set up my old gear with it's LCD displays on the outside of the grow tent. I've received the OnePen already and will dive into it as soon as I set up the gear, thanks!

I appreciate you Noel! Cheers mate!

Appreciate that! Thanks for watching amigo.

Thanks amigo. Appreciate your support as I get going again. Make sure you’re subbed! :)

Hey there Steve and Ted. Thanks so much for the support - glad to be back! It’s good to hear about your first greenhouse hydroponic pepper grow in New Zealand. Using Hydroton in a Dutch bucket setup is a solid choice. Here are some tips that should help you get the best out of your system: pH and nutrient strength management: You’re right to focus on pH and CF. For peppers, try to keep the pH between 5.5 and 6.5 for optimal nutrient uptake. Regarding CF (Conductivity Factor), you want to aim for 18-24 (EC 1.8 - 2.4) during the vegetative stage and around 22-30 (EC 2.2 - 3.0) when they’re fruiting. A good EC/CF meter will make this process much easier. Bluelab are your local goto here! One of the great things about Hydroton is its excellent aeration and drainage properties. Make sure to rinse the clay pebbles thoroughly before use to get rid of dust, which could clog your system. While Hydroton is very forgiving when it comes to aeration, you’ll still need to find the right watering balance. The pebbles drain well, but if your irrigation is too frequent, the roots could stay too wet, leading to potential issues like stunted growth or root rot. In a Dutch bucket setup, you generally want to run the pump for 10-15 minutes every few hours depending on your environment (especially humidity and temperature). This will allow the roots to access water and nutrients without staying too soaked. Decrease frequency of irrigations when you want your peppers to start flowering and fruiting. Make sure your system is draining properly between cycles. This is key to preventing over-saturation of the root zone. Even though clay pebbles provide excellent aeration, allowing some dry periods for the roots to "breathe" is still important. Best of luck with your grow! Hydroponic peppers are an exciting project, and your setup sounds like it’s off to a great start. Feel free to ask more questions as you go - I’ll be growing jalapeños indoors while you’re enjoying the southern hemisphere summer!

Thanks for watching!

Mmmmmmmmoist!

More to come! Updating the grow room for a 2025 renaissance.

And so many others! :) :)

Yeah man. Never felt better! Thanks :)

@@Just4Growersplease do a video on coco in autopots 🙏

Vinegar mixed with dishwashing detergent sprayed on. Acetic Acid dissolves calcium and lime and dish detergent solubilises in water.. you still need to rinse in water

I would be interested to know your water source and starting EC. Simply increasing the strength of the base nutrients may risk oversupplying other elements like nitrogen (N), phosphorus (P), or potassium (K), leading to imbalances. This can cause nutrient toxicity or deficiencies over time, particularly in sensitive strains. If your water source is extremely soft and lacks calcium and magnesium, the calcium and magnesium levels in the base nutrient formula may not be sufficient even at higher concentrations. You lose the ability to finely tune these two key nutrients independently of others. Increasing the base nutrient strength can raise the overall electrical conductivity (EC) of the solution, which may stress the plants, particularly in sensitive stages like early veg or flowering.

No more HPS for me but I love watching old videos on them

Great suggestion! It’s on the list.