High quality thermometer hydrometer

[Smallgrow]

…The other post talking about VPD got me thinking I should post this for all in a new thread

A while back when I started to get serious about VPD ( yes it’s important ), I was troubled by all the different readings I got on all the different devices I have.
That’s 4 Grovee thermometer/hydrometer, 6 mini thermometers/hydrometer for jars (cheap), 2 AC Infinity controllers , 2 inkbird temp and 1 Inkbird humidity controllers. I think that’s it
Anyway, I averaged them out (like some other smart person said) and then adjusted them all to that, but I still wasn’t convinced. Temp and humidity (and watering) are critical in our gardens, everything else is secondary IMHO.
It occurred to me that real scientific labs and other places like that are not gonna put up with random guessing about those things, so there must be a more trustworthy and accurate device out there. So off to google I went, and sure enough

https://www.coleparmer.ca/i/traceable-thermohygrometer-with-alarm-and-calibration-external-sensor/9876685

This is just one example, if you look up Traceable products you can find more. The whole point is they are guaranteed to be accurate, and have relatively tight tolerances. They are pricey but 130-150 Canadian is not out of sight considering the importance. I’m going to order one and use it to calibrate all the others on a regular basis in hope I will be more precise in my growing, and have better results.

Hope people find it helpful.
Grow on!

[9fingerleafs]

I use Xiaomi mijia hygrometers. The square ones. They're super cheap but very accurate. Bluetooth so you can check them without opening jars or outside a tent/closed room. Been using them for 3 years. Got 6 of them and have replaced the batteries several times. Unlike the black small ones that when you take the battery out they deconfigure. They're like 20 bucks each and it's better to have several than one expensive one in my opinion

[3Berries]

I use to work in a chem lab checking thermometers and hydrometers for accuracy the Navy used in our submarine batteries we made. We used a mercury 32F to 108F in 1/10F degree graduations and it was traceable. When they closed the place up it found a home with me I've found most high quality temperature controllers to be pretty accurate. Can't say the same for hygrometers though. If I can get them to read within a couple percent and still be able to read 100% I'm happy.

Going off the VPD value you fuss with the temp first then humidity to get the VPD range right. And so much depends on the health of the plant, leaf area as that is what is adding the humidity naturally. Or really high powered lights that requite a lot of air movement, forget about VPD there. Slow and low for the fan speeds if you can.

I usually have a problem in flower getting the VPD in range without adding a lot of humidity with a mister of wet towels. This run I have three plants instead of two and the tent is packed, humidity is naturally a lot higher..

[90Gizmo]

Smallgrow That is so cool. I got a nist traceable veneer caliper when I worked for a metrology company. I was a software manager so it was mostly for show but I took it with me when I left. The price of the meter seems very doable. When I become a room-scale grower that will be a must. How accurate are those wet/dry whirligigs? Seems like that might enough for occasional calibration.

[Smallgrow]

Looks like the one I linked accuracy is +\- 0.5C for temp and 3% between 25-75% on the humidity side. Which is better than any of the ones I have I think