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Do all non-electronic hygrometers suck?

I had a couple of mechanical hygrometers in my grow chamber.  I didn't really trust them, so I bought an electronic one.

Very different readings, and I trust it more.

The mechanical hygrometers showed humidity dropping overnight as the temperature dropped (with the lights being off), but I suspected relative humidity should increase, as the air cools and saturates.

The electronic hygrometer showed that happening; it shows relative humidity at >95% overnight, and about 63% during the day.

The dramatic change in relative humidity has to do with how much moisture the air can hold, more than any real drop in the percent makeup of water vapor in the air.

Will such a drop in relative humidity be detrimental to Nepenthes such as N. bicalcarata?
 
Yes, they are good. Its just that if you need the absolute to the "T" reading then you would go wit electric. I have a mechanical that I know is farely accurate. My tank is usually 75% but when I water it goes to 95% or so and slowly drops off during the day. It may not be right on but I know by smaelling the air if humidity is at decent levels and if it rises with added moisture it can't be terribly far off. I would suggest a quality hygrometer though, such as ZooMed or Hagen/ExoTerra. My Exo has been around for 3yrs now.



Joe
 
I have one of those stick-on hygrometers they have at pet shops for reptiles, and it works pretty good in my fluorescent terrarium, but make sure you don't get them wet. I don't know why, but it busts them. I used to have one with my outdoor plants in the greenhouse, but I think it got wet from all the misting and it crapped out on me.
 
Scott, I don't think your electric hygro is that accurate, either. You shouldn't be seeing a 30% jump in humidity with just the shutoff of your lights. I just checked the graphs from my terrarium therm-hygrometer(I use one of my weather station sensors to get humidity and temp measurements), and nightly I get about a 10 degree drop in temp, but on average a 2-6% increase in humidity.

Just out of curiosity, do you have a fan in your tank? If so, does it shut off when your lights do, as well? If so, that would probably be the reason for a 30% difference. I seem to remember back before I got a reliable fan, the humidity would shoot up like that overnight and I'd be greeted in the morning by a foggy tank.

Sam
 
[b said:
Quote[/b] (GaWd @ April 03 2005,2:42)]Scott, I don't think your electric hygro is that accurate, either. You shouldn't be seeing a 30% jump in humidity with just the shutoff of your lights. I just checked the graphs from my terrarium therm-hygrometer(I use one of my weather station sensors to get humidity and temp measurements), and nightly I get about a 10 degree drop in temp, but on average a 2-6% increase in humidity.

Just out of curiosity, do you have a fan in your tank? If so, does it shut off when your lights do, as well? If so, that would probably be the reason for a 30% difference. I seem to remember back before I got a reliable fan, the humidity would shoot up like that overnight and I'd be greeted in the morning by a foggy tank.

Sam
No, I think that jump might be right. When the lights turn off, I can see the vinyl sides dew up.

There's no fan in there.
 
I think with no fan you might see that jump in humidity. Like I said, before I got a reliable fan, or any fan at all, I used to have problems with fog and such. Now I have my fan on full-time, and I don't have the same effect.

Sam
 
my tank never fogs up, but theres always fog floating 1/3 up the tank

is it because it's an open-top tank that i never have foggy glass?
 
Mechanical hygrometers (analog) are just as accurate as the digital ones, problem is, the accurate ones are like $50.
 
Scott, those are perfectly normal changes in RH for a 10-15 degree temperature drop. Dunno about the N. bicalcarata.
 
  • #10
There's usually an approximately 10-degree night/day temperature difference and an approximately 10% night/day humidity difference with mine, and there's always dew on the glass, moreso at night than during the day, and I haven't misted in there for months. No fog though.
 
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