Perlite Lowered My Humidity?

Nan's Nook : Archives : Grow Chambers & Clean Rooms : Nan's Nook Fruiting Teks Q&A: Humidity: A Good Hygrometer : Perlite Lowered My Humidity?
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By Shroomzila (Shroomzila) on Monday, February 18, 2002 - 03:47 pm:

I have been doing some experimentation with my terrariums before I get to growing. The first thing I did is rig an Ultrasonic Humidifer up to my two 60 qt. tubs, then used a digital hygrometer to tell me the humidity, with-in an hour both tubs were up to 92% humidity. I wanted to get the humidity higher (between 95%-100%) so I then added 2 inches of Perlite to the bottom, with 1/2 inch of water in it. Also I put two aquarium heaters in sealed 1.5 Liter bottles to start experimenting with temperature. I left the Ultrasonic Humidifier on all night, along with everything else, and too my shock, the humidity will now, never surpass 78% in either terrarium. What the heck is going on here? For some reason is the perlite actually lowering my humidity? Or does it have something to do with the evaporation properties of the aquarium heater? Any information would be greatly appreciated.

By Shroomzila (Shroomzila) on Monday, February 18, 2002 - 04:16 pm:

Also, should the perlite be tightly or losely packed? Thanks.

By Maliki vision seaker (Maliki) on Monday, February 18, 2002 - 04:39 pm:

Im at using just the peralite now and the cool mist for gas exchange only. I also found that with the humidifier goining i couldnt get the humidity up past 80% or so. When I leave the humidifier off my humidity goes up to 90% or so. When I put a heating pad under the bins the humidity jumped to 100%in an hours time but the temp hit 90 in around 12 hours time no good for fruiting. I think The low humidity has to do with the constant gas exchange. Or the peralite could be absorbing the humidity instead of relaseing it.

I put my perlite in a screen drainer run hot water over it let it drain untill it just drips then layer the bottom of the bin.

By Shroomzila (Shroomzila) on Monday, February 18, 2002 - 04:51 pm:

Ok, I'll keep on experimenting until I reach perfection! (If thats possible. :) Thanks for the info Maliki!

By Nan (Nanook) on Monday, February 18, 2002 - 07:18 pm:

How much did you pay for your RH meter?

By Maliki vision seaker (Maliki) on Monday, February 18, 2002 - 07:42 pm:

Missed that sorry. But wouldnt the change in levels still show decress and incress on the metter regardless of acuracey in actual humidity percentage ?

By Nan (Nanook) on Monday, February 18, 2002 - 08:16 pm:

Not on a cheap digital meter it won't. They get over 92-93% humidity and they go wacko. I have seem them go to zero, 20% (when droplets were condensing on the meter face) or just display garbage. Sometimes they recover if you dry them all the way out again :) But the bottom line is you simply cannot trust a cheap digital relative humidity meter in this application. They are a frustrating waste of time, energy, and money.

If you are going to use a meter, pony up the cash and do it right. Most people don't need one. I like the one Nuecrew researched out. This is a very good quality instrument for the money. The cigar shop where I got mine did not carry it, but they were able to order it for me.

By Shroomzila (Shroomzila) on Monday, February 18, 2002 - 08:28 pm:

I paid $25.00 (us dollars) for it. Is this a bottom of the line one? It's called the Tri-View (indoor - outdoor Digital Thermometer with hygrometer & clock.

By Nan (Nanook) on Monday, February 18, 2002 - 09:22 pm:

Sorry :( Your humidity is fine, it's your meter that is giving you the fits. None of the multi-purpose intruments I have seen retail are suitable. I am quite sure your Tek is delivering close to 100% RH, and it was after adding the Perlite that it shot so high the meter wacked out on you. Don't believe it, it is lying to you.

By Shroomzila (Shroomzila) on Monday, February 18, 2002 - 09:32 pm:

OK, Glad to hear the humidity should be fine. Your right the meter has been fluctuating up and down, but now (for the last hour or so, it reads 99%). Thanks for the info Nan.

Hey No Problem! - Nan

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