Which One is Correct?

Indoor Growing Climate
1

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

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IMG_00063888×2592 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_00113888×2592 1.43 MB

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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…

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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.

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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.
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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.

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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.

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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.

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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).

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

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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.

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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
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@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.

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

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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?

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