Which One is Correct?

Indoor Growing Climate
1

Take your pick. They are all reading the same environment.

IMG_0006
IMG_00063888Ă—2592 1.54 MB

The ThermoPro transmitter is sending a rh of 38 while the base unit is reading 33 for the same location.
The larger unit is a Growers Edge. You can see the transmitter is sending 43% to the base unit (channel 1). However, the base unit reading itself is 30% (no channel) WTF??
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IMG_00113888Ă—2592 1.43 MB

2

I would probably just take an average of them all. Not really sure how to tell which is most accurate, 10% difference is kind of a lot.

Glad I only have 1, lol…

3

That would be typical for cheap instrumentation. A lab grade thermometer is about a hundred bucks but I’m not going to pay that for one. I’m using the same thing you got.

4

Try this. You want a slurry of salt, not salt water.

  1. Place a teaspoon of salt in a bottle cap or small cup and dampen it with a few drops of water (without dissolving it).
  2. Carefully place the wet salt and the hygrometer inside a see-through container and close tightly. You can use a zip lock bag provided it seals well and you leave some air inside as well.
  3. Let it sit for at least 6 hours and note the reading on the hygrometer without opening the container. The hygrometer should should read 75%. The difference is how much your hygrometer is off. For example, if your hygrometer reads 70% during the salt method test this means that to obtain the real humidity level you should add 5 points.
  4. If you have an analog hygrometer, you can correct the reading. You will need to adjust the needle to the 75% mark by turning the screw on the back using a small screwdriver. Your hygrometer is now ready to be placed inside your humidor.
5

Yep - saw that somewhere and was planning on doing that. Also, I have 62% Boveda packs. I would think one could use them too. Appreciate the follow up.

6

Home use Hygrometers are typically +/- 3% or +/-5%.

To get more accuracy you would need to go with lab grade equipment which would be very expensive and usually require separate display with a 0-10 volt or 4-20 ma output for display or control.

Even my instrumentation grade hygrometer is +/-3% and it cost $100.

7

I think I will make due with what I have and figure out an adjustment using salt mix or Boveda packs in a plastic bag.

8

I need to clarify, I was not suggesting that you should purchase different hygrometers, I use the same ones that you have for my curing tubs.

I was pointing out that these sorts of devices have an intrinsic accuracy and you can expect them to differ within that accuracy range.

The reason that I have the instrumentation grade device is that the device sends a 4-20 ma signal to my controller which in turn controls my fans, dehumidifier and humidifier (that is addition to controlling all of the various lights).

9

No misunderstanding. All I was saying is for my purposes, close is close enough.

10

With hygrometers, close is as good as it gets and that certainly as good as we need outside the lab or highly sensitive manufacturing environments.

11

The winner is Grower’s Edge. I put a 62% Boveda pack in a Hefty Ziploc and put both transmitters in the bag. They have been in the bag a couple of days. I am surprised how long it actually took.

Humidity Read
Humidity Read3888Ă—2592 1.6 MB

@merlin44 @GoneFission @kellydans @Ron330 @nicky - I thought I saw you have a ThermPro
When I had both transmitters in the tent I would have swore the ThermPro was the correct reading. Apparently have to add 5%. At least temp is consistent. Put this in For What its Worth category.

12

Yeah good call.
I did the same with a bunch of small ones to

13

Oh, I made that angry noise, ugh!Gra!
Just to have equipment I can trust, thats all I want.

Whats a new grower to do?