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boogiem0nst3r
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Registered: 02/23/10
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Two Hygrometers - both calibrated - Diff readings inside FC *pics*
#12535456 - 05/10/10 03:24 AM (14 years, 8 months ago) |
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Hey All,
I have two hygrometers, both are analog and calibrated via towel method (to 99%). One (my original one) I bought from a local cigar shop. The second one (I bought it just to have/cuz its good deal) was from ebay someone posted a link a while back on here, $5 shipped and it looks like the one everybody has.
I put both hygrometers side by side against the wall of my shotgun FC and one reads 80% while the other is like 92%. So I'm thinking one of them must be off, so I went to check its calibration (via damped towel)
After one hour I pull both hygrometers out of the towel and they both read 99%, so why the different readings inside the FC?
_boogie.
Edited by boogiem0nst3r (05/10/10 04:26 AM)
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boogiem0nst3r
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: boogiem0nst3r]
#12535510 - 05/10/10 04:25 AM (14 years, 8 months ago) |
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The one on the LEFT is the one I got recently from ebay (CLICK HERE)
and the one on the right is one I got from a local Cigar shop.
As you can see both of them have different readings while inside the FC, although they are just both freshly calibrated. So what gives?
_boogie.
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RogerRabbit
Bans for Pleasure


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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: boogiem0nst3r]
#12535702 - 05/10/10 06:58 AM (14 years, 8 months ago) |
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I would suspect there's more air entering the holes behind the lower reading one. Try switching positions to see if the other one reads lower.
Or, try putting them both in the middle away from the holes. If they still read different, chalk it up to cheap junk from china, which is all we get anymore. RR
-------------------- Download Let's Grow Mushrooms
semper in excretia sumus solim profundum variat
"I've never had a failed experiment. I've only discovered 10,000 methods which do not work."
Thomas Edison
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boogiem0nst3r
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: RogerRabbit]
#12538545 - 05/10/10 05:34 PM (14 years, 8 months ago) |
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RR,
I switched them and it still remains the same. I then moved it towards the center, and laid it against my tray. The big one on the right reads about 95%, while the other one (smaller one) reads about 80%.
Which do I trust, I'm guessing the big one, as I have a LOT of perlite in my chamber (about 5-6"). Temp is at roughly 70-75 the whole time, 1/4" holes every 2 inches all 6 sizes. Bottom is elevated 1.5" off the surface.
Don't understand why they remain calibrated (works fine when I calibrate it with towel) but in chamber they have different readings?
_Boogie.
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fastfred
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: boogiem0nst3r]
#12539138 - 05/10/10 07:02 PM (14 years, 8 months ago) |
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Use moistened salt for proper calibration. A dampened towel is just a very rough calibration method.
Just google "salt calibration hygrometer" and you should find plenty of articles.
-FF
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teknix
𓂀⟁𓅢𓍝𓅃𓊰𓉡 𓁼𓆗⨻


Registered: 09/16/08
Posts: 11,953
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Re: Two Hygrometers - both calibrated - Diff readings inside FC *pics* [Re: boogiem0nst3r]
#12539174 - 05/10/10 07:06 PM (14 years, 8 months ago) |
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I would guess the one on theleft is right, looks pretty dry from the pics.
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Bojangles
( . Y . )




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Re: Two Hygrometers - both calibrated - Diff readings inside FC *pics* [Re: teknix]
#12539199 - 05/10/10 07:09 PM (14 years, 8 months ago) |
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i hope the one on the left is right cause i just bought one haha
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everything i say is bullshit...
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Barakanaten
Ama-gi




Registered: 04/14/10
Posts: 6,163
Loc: PNW Mycosphere( Blessed C...
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: fastfred]
#12539269 - 05/10/10 07:21 PM (14 years, 8 months ago) |
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I have two of the ebay hygrometers from the same link and I have preformed ten different tests. Here are my conclusions.
I find the salt method to be more accurate.
Before you put the meters in the bag with salt dial them down a bit.
Follow the instructions to the salt calibration method to the t.
In two hours they will both read 75% but after 4 will read 80%
Make quick work of caliberating the units once out of the bag as they will IMMEDIATELY start to drop. also I found that when I removed the unit for calibrations the one still in the bag starts to drop before you get a chance to calibrate.
Last little tip here but press firmly on the glass portion and the housing when turning the calibration screw because i have found the housing will turn with it. Also when turning the screw do not let the screw driver go to deep into the screw touching the metal the screw rests on, it will bend and mangle the cheap metal screw then can make the screw catch the backing and thus turns the housing...Hope this helps Oh and also to note after calibration I have set them in open air side by side and they have eventually had different readings. But when stacked on top of each other in the same spot in open air the units read in sync. When they read 75% just turn the screw to 99. Use one bag for 1 unit. Salt Calibration Click me!!!!
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New to cultivation? Have a Question? Because AMU We Q&A Know AMU Genetic Library Easy Felt  AMU  Official PNW Mushroom Hunting Season 2011"...Though in all else he may be as Saintly as St. Francis, in the pursuit of these ends he is more
Satanic than Satan. He will betray his nearest and dearest without the slightest twitch of flesh or spirit.
He is amoral."
-Definition of a mushroom hunter by ~Angelo Pellegrini
Edited by Barakanaten (05/10/10 07:54 PM)
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RogerRabbit
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: fastfred]
#12539375 - 05/10/10 07:35 PM (14 years, 8 months ago) |
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Quote:
fastfred said: Use moistened salt for proper calibration. A dampened towel is just a very rough calibration method.
Just google "salt calibration hygrometer" and you should find plenty of articles.
-FF
The salt calibration is not as accurate for our use. It calibrates in the 75% range, and mushroom terrariums operate in the 90% and greater range.
A damp towel is not a rough calibration. It's saturation humidity, and calibrates the hygrometer very close to where it's going to operate. No instrument is linear in accuracy, so you always want to calibrate as close to the actual use parameter as possible. RR
-------------------- Download Let's Grow Mushrooms
semper in excretia sumus solim profundum variat
"I've never had a failed experiment. I've only discovered 10,000 methods which do not work."
Thomas Edison
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tajmahal420
Stranger than some....

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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: RogerRabbit]
#12539518 - 05/10/10 07:58 PM (14 years, 8 months ago) |
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I don't see how salt calibration can be accurate for use in ANY range.
Seriously, how the hell do you even know that the humidity in the bag is 75%. One drop of water too much or too little could change that percentage, especially with just a bottle cap full.
That seems pretty rough, but that's just my opinion.
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Barakanaten
Ama-gi




Registered: 04/14/10
Posts: 6,163
Loc: PNW Mycosphere( Blessed C...
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: RogerRabbit]
#12539546 - 05/10/10 08:03 PM (14 years, 8 months ago) |
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Quote:
RogerRabbit said:
The salt calibration is not as accurate for our use. It calibrates in the 75% range, and mushroom terrariums operate in the 90% and greater range.
A damp towel is not a rough calibration. It's saturation humidity, and calibrates the hygrometer very close to where it's going to operate. No instrument is linear in accuracy, so you always want to calibrate as close to the actual use parameter as possible. RR
hmmm if the unit read 75 and I quickly moved it to 99 would that work?
or what your saying is that the differences in environment play a factor in the different types of RH the units will be experiencing?
Totally just trying to grasp the concept and not at all questioning your knowledge. thanks
Edited for newbness: I re read and I get it now, makes sense
Edited by Barakanaten (05/10/10 08:20 PM)
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boogiem0nst3r
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: Barakanaten]
#12540970 - 05/11/10 12:15 AM (14 years, 8 months ago) |
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so does anyone else have experience with this hygrometer (from this thread)? it seems like a piece of crap to be honest, I had high hopes for it (it being analog, and a lot of people use it?)
thanks,
_boogie.
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Barakanaten
Ama-gi




Registered: 04/14/10
Posts: 6,163
Loc: PNW Mycosphere( Blessed C...
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: boogiem0nst3r]
#12541062 - 05/11/10 12:37 AM (14 years, 8 months ago) |
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I have the exact same two and so do tons of people here.
After doing some searche's and finding RR's reply's to countless threads asking the same thing I found this:
Bottom line is Wrap it in a soaked towel for about 30 min or so.
After that set it to 98%.
do a search on hygrometer calibration and see that RR says the same thing even as for back as 3 or 4 years ago. lol poor guy gets the same question over and over ...lol
He explains the reason is you should calibrate the unit in the setting it will be used for. very humid.
Caliberation debate
Quote:
No. You calibrate any instrument in the environment it's going to operate in, because no instruments are accurate through their entire range. The salt test is great for a cigar humidor because that's roughly the humidity they operate in. Our greenhouses and terrariums operate in the 90% to 99% humidity range, thus we calibrate them with the wet towel method for better accuracy. RR
once i finally read this I got it. Hope this was helpful
This was a bad idea
--------------------
New to cultivation? Have a Question? Because AMU We Q&A Know AMU Genetic Library Easy Felt  AMU  Official PNW Mushroom Hunting Season 2011"...Though in all else he may be as Saintly as St. Francis, in the pursuit of these ends he is more
Satanic than Satan. He will betray his nearest and dearest without the slightest twitch of flesh or spirit.
He is amoral."
-Definition of a mushroom hunter by ~Angelo Pellegrini
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boogiem0nst3r
Stranger
Registered: 02/23/10
Posts: 90
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: Barakanaten]
#12541084 - 05/11/10 12:45 AM (14 years, 8 months ago) |
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Hey,
I don't mean to be rude, but were you responding to me? If so maybe You misread my posts, but I already calibrated it via towel method, and calibrated it to 98-99%. I test the calibration as well by taking it out and re-wrapping it later, and wa la both hygrometers show 98-99% when in the towel.
My issue is one of the hygrometers, the one listed in the link above (note, i have TWO entirely different hygrometers, as shown in my picture above) the one in the ebay link, seems to be faulty somehow. But I don't know whats causing it, or if its just a piece of crap.
_boogie.
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Barakanaten
Ama-gi




Registered: 04/14/10
Posts: 6,163
Loc: PNW Mycosphere( Blessed C...
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: boogiem0nst3r]
#12541110 - 05/11/10 12:52 AM (14 years, 8 months ago) |
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Hey no worries, I have two of them and tested them in my bathroom alongside a digi hygrometer and all three read the same thing. Not sure if yours is faulty or not. I really wish I could be of more help but I am a n00b and am sure someone will have a better answer.
--------------------
New to cultivation? Have a Question? Because AMU We Q&A Know AMU Genetic Library Easy Felt  AMU  Official PNW Mushroom Hunting Season 2011"...Though in all else he may be as Saintly as St. Francis, in the pursuit of these ends he is more
Satanic than Satan. He will betray his nearest and dearest without the slightest twitch of flesh or spirit.
He is amoral."
-Definition of a mushroom hunter by ~Angelo Pellegrini
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chemestre
human



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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: Barakanaten]
#12541404 - 05/11/10 03:04 AM (14 years, 8 months ago) |
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SWIM has cheap junk from china. it usually reads at about 85% humidity in his FC. only thing is, he knows thats a bogus reading, because he has both perlite going, and a bubblier. and on top of that, lives along the gulf coast, where spring/summer humidity levels stay between 70-90% regularly...
just dump a ton of wet perlite in the FC, and hope for the best!
-------------------- *DISCLAIMER: i am a pathological liar. everything i post is false. any pictures i post have been stolen from elsewhere on the internet.*
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RogerRabbit
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: chemestre]
#12542064 - 05/11/10 09:13 AM (14 years, 8 months ago) |
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Quote:
My issue is one of the hygrometers, the one listed in the link above (note, i have TWO entirely different hygrometers, as shown in my picture above) the one in the ebay link, seems to be faulty somehow. But I don't know whats causing it, or if its just a piece of crap.
It's a piece of crap, just like every thing from china. You can thank walmart shoppers for the fact that we can't get ANYTHING of quality any more. When a good analog hygrometer was $20 and made in USA, you knew what you were getting and it worked. When everyone went for the cheapest price no matter what, all that became available was crap from china. A stinking rock would probably be as accurate as that chinese toxic waste they disguise as consumer products.
Here's what to do. Toss BOTH of those so-called hygrometers in the trash and build your terrarium per the tek and guess what? Your humidity will be in the proper range. RR
-------------------- Download Let's Grow Mushrooms
semper in excretia sumus solim profundum variat
"I've never had a failed experiment. I've only discovered 10,000 methods which do not work."
Thomas Edison
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bare.whiterabbit
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: RogerRabbit]
#12542099 - 05/11/10 09:25 AM (14 years, 8 months ago) |
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Funny, I have both of those. I simply prefer to think of the smaller, heavier and better built one from the cigar shop, that cost almost as much as my hygro/thermo of the same brand as your larger one, as the more accurate.
Most of the time it reads right where it should, even in the 99-100% range.
Edit: Sorry, the large hygro I speak of is a Raumklima thermo/hygro, cost $30 from my hydro shop, but the little one I got is like the one on the right of your picture and I love it, it seems to work very well as I said.
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Edited by bare.whiterabbit (05/11/10 09:28 AM)
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fastfred
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: tajmahal420]
#12549858 - 05/12/10 04:35 PM (14 years, 8 months ago) |
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Quote:
tajmahal420 said: I don't see how salt calibration can be accurate for use in ANY range.
Seriously, how the hell do you even know that the humidity in the bag is 75%. One drop of water too much or too little could change that percentage, especially with just a bottle cap full.
Maybe you should actually look up the principle of salt calibration before posting.
Salt calibration works because salt will absorb and release moisture at a specific humidity. When the humidity is greater it absorbs water when it's less it will release moisture. At 25C saturated salt will always produce 75.3% RH. It's also pretty stable across temperatures, at 20C it's 75.7.
I don't know how accurate the towel method is. Like RR said it's always best to calibrate near your desired measurement range. I would think that a wet perlite method would probably be more effective at attaining saturation humidity.
Anyways there's too much worrying about humidity. If you use perlite your humidity will be right. There's no reason to worry about what inaccurate hygrometers read.
-FF
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camplo
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Re: Two Hygrometers - both calibrated - Diff readings inside FC [Re: fastfred]
#12550143 - 05/12/10 05:13 PM (14 years, 8 months ago) |
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Well if the analog ones are all from china and crappy, I'd say the proper digital should be choice. Just as long as its not one the kind with just a pin hole to introduce air to the sensor but instead one that was plenty of ventilation to the sensor. Then of course the analog would be around for when the batteries in the digi die and you need something right away.
I would imagine if you calibrated them both in a wet towel that the one reading the lowest is incorrect.
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