Climate zones and how to measure "real" VPD

snekonomics

snekonomics

Member
I've set up monitoring and automation for my tent, but I've found that different factors change the readings significantly and now I'm not sure if the readings I get are even worth anything. The question is which climate zone is the one that would give the most accurate info of what the plant actually "feels"?

Canopy level makes the most sense, but the measurements with the big fan on throws me off. Increased airflow (which should be good) results in higher humidity and lower VPD.

Here's a pic of my tent and the zones. Note: canopy-level measurements were taken with the sensor facing downwards. When flipped and exposed to light (as the the canopy is), measurements are 29.1°C with 62.9% RH. The lower fans are always on.

climate zones.jpg
 
Lockedin

Lockedin

Well-Known Member
snekonomics said:
The zone is only part of the question, the effect of the increased airflow reflected by the numbers is confusing.
I have VPD calculated and logged by the controller.
Click to expand...
1st - love the set up! I'm going to emulate those lower circulation fans soon.

Airflow - I don't see an exhaust fan. Hot air will rise and exhaust passively, but a fan pulling through the exhaust will be more effective - especially in a smaller space.

If you do install an exhaust fan, you can set it lower than you might think - you don't need a force-5 hurricane, just enough pull to exchange the stale air with fresh air in all the zones at a cfm that someone more experienced than me says to.
Your space may be too small for this (and occupied with a nice looking plant!), but I went inside mine with the zippers closed to feel the intakes - very light breeze on the back of my hand.

I just use a cheap Vivosun 4" through Veg - I need to get another before flower, the bigger 4" vivo is probably going to take a crap on me - again.
 
NukaKola

NukaKola

Well-Known Member
VPD is based on leaf surface temperature not ambient air temp. Grab an infrared thermometer and point it at the leaves.
 
snekonomics

snekonomics

Member
Wastei said:
All data is good for future reference. But it will never be as important as to read the plants. They will tell you what to do.
Click to expand...
The plant has been happy throughout the grow, but it's just I'm worried about high humidity causing me pest problems. It's my first grow and don't want to screw it up.
Lockedin said:
1st - love the set up! I'm going to emulate those lower circulation fans soon.

Airflow - I don't see an exhaust fan. Hot air will rise and exhaust passively, but a fan pulling through the exhaust will be more effective - especially in a smaller space.

If you do install an exhaust fan, you can set it lower than you might think - you don't need a force-5 hurricane, just enough pull to exchange the stale air with fresh air in all the zones at a cfm that someone more experienced than me says to.
Your space may be too small for this (and occupied with a nice looking plant!), but I went inside mine with the zippers closed to feel the intakes - very light breeze on the back of my hand.

I just use a cheap Vivosun 4" through Veg - I need to get another before flower, the bigger 4" vivo is probably going to take a crap on me - again.
Click to expand...
I have an exhaust fan and filter mounted outside the tent.
NukaKola said:
VPD is based on leaf surface temperature not ambient air temp. Grab an infrared thermometer and point it at the leaves.
Click to expand...
I have a monitoring setup that calculates leaf VPD already, adjusted to real leaf temps. My concern is about where to measure and if the raised VPD due to extra airflow at canopy is worth it or has any effect to begin with.

1600784317277.png
 
2cent

2cent

Well-Known Member
In that space turn off the fan and centralise ya intake below.
The extraction should be more than way more than enough that tent is like a cooltube grow man
Utlise the space as a fan dont use a fan u less ur in 2.4mx1.2m space or more
 
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