Mixed RH readings - which should i trust?

[shiva71]

Hi
I have an analogue thermo/hygrometer, which i bought because i didnt trust the cheap digital ones. Got a dehumidifier last week. They both agree temps are 24°, however for RH the analogue is giving me 50%, my dehumidifier is telling me 32%. Quite a difference.
Which of these two is more likely to be accurate?
Thanks!
Neil

 

[insomnia65]

I'd buy a cheap one on amazon or ebay and compare the 3.

 

[Creature1969]

Look up calibrate hygrometer. You can use a Boveda pack or salt water to check how far off they are.

 

[SnidleyBluntash]

Are they in the exact same spot? I don’t trust anything, I use the numbers more as a guide. If one is closer to the plants it could read higher.

 

[Star Dog]

Mix up salt and distilled water to a paste (wet sand) in a small tub, put it in a zip lock bag with the rh% meter and leave at 25c.
That's a known rh% of 70% at 25c, you need to leave it 2/3 hours to settle before taking reading/calibration.

 

[shiva71]

Ok thanks. Yeah I read about the salt paste check method, I won't be able to put the dehumidifier in a zip lock bag but I can check the analogue one.
Put a 3rd one in there, another digital one i had, that agrees with the humidifier at 32%, analogue reading 50% so its maybe thats the one that is out.
Cheers!

 

[Star Dog]

Ok thanks. Yeah I read about the salt paste check method, I won't be able to put the dehumidifier in a zip lock bag but I can check the analogue one.
Put a 3rd one in there, another digital one i had, that agrees with the humidifier at 32%, analogue reading 50% so its maybe thats the one that is out.
Cheers!

I read to wrap a analogue rh% in a damp cloth overnight and it should read 100%, idk how accurate that is but I read it somewhere in the past?

 

[Dontjudgeme]

My dehumidifier has its own hygrometer also, which is why I don’t have it connected to my inkbird, I only use my inkbird for my humidifier. The dehuey probably kicks on a few percents before the inkbird would have turned it on if it was connected to it, so they seem pretty close in regards to readings. But the gap you’re experiencing seems pretty drastic. If it were me, I would trust the dehueys readings.

 

[shiva71]

Hmmmm. The analogue has been in the bag with salt slurry about 5 hours and its reading bang on 75% which is what it should say. I cant believe my humidifier is 20% out...?

 

[Star Dog]

Hmmmm. The analogue has been in the bag with salt slurry about 5 hours and its reading bang on 75% which is what it should say. I cant believe my humidifier is 20% out...?

It's been a while I thought it was 70%, anyway I'm not surprised it's out so far if it's one of the tape/mechanical ones, they're not the most sensitive.

If you have access to the dehumidifier control there's usually a screw for adjusting it.

 

[shiva71]

Appreciate the replies guys cheers!
Still getting the analogue 50% humidifier 30%. The analogue has been checked with the salt method that seems to be accurate.
Dammit this shouldn't be a problem!!

 

[Southernontariogrower]

Appreciate the replies guys cheers!
Still getting the analogue 50% humidifier 30%. The analogue has been checked with the salt method that seems to be accurate.
Dammit this shouldn't be a problem!!

Wait till your ph pen sarts going out, fun times begin.

 

[shiva71]

Actually that's the only thing working! Essentials. Good pen. My 2 ppm meters are also out!