Re: Somthings really wrong..
 

I woke up last night to go to the bathroom, interrupting a dream of coconut pudding and sweet beans mixed with it.

Still half-asleep, a thought came to mind about the humidity problem, which was that the air immediately adjacent to the ice bottle gets cold, forcing water to come out of the cold air. Continuing the example, air at 0 degrees C. can hold only 6 grams of water for each cubic meter of air. Water at 20 degrees C. holds 17 g./m3 of water at 100% RH. When that air is cooled to 0 degrees C., 11 g./m3 of water has to come out of the air. That water appears in the form of condensation on the ice bottle.

The cold air immediately adjacent to the ice bottle eventually moves away and is warmed up, automatically reducing the RH since warmer air holds more water. This process of cooling some air, then warming it up, reduces the humidity of the air in the terrarium. It's true that the temperature of the air in the terrarium is also reduced, but not enough to overcome the effect of the reduced RH.

I didn't stay awake long enough to figure out how to reduce the temperature of the air in the terrarium without reducing the RH.

I went back to sleep hoping to eat that dessert in my dream.

Re: Somthings really wrong..
 

Place an aquarium air pump in the water tray in the terrarium. That would increase humidity in the terrarium. Just leave a small gap on the lid of your terrarium so that humidity can be kept in the terrarium. Alternatively if you can place those sonic humifier (not sure what they are called) to create a mist in the terrarium. This humifier breaks water into mist by using high frequecy sound. You get get it ad garden centers or aquarium shops for about RM50-RM60.

Re: Somthings really wrong..
 

I am no expert in this, I just googled it, so these are just from what I understood.

1. JK, I think your calculations are correct. Now let us try to simulate what happened with Ken's.
Let us assume:

30C with 87%RH
Which means: 87%/30 x 100 = 26.1g/m3

At 20C (assuming he was able to cool it down to that level only)
he started with 26.1g/m3
So 26.1g x 100%/ 17
RH at 20C is 153.52% ????

But, because at that temperature air can only hold 17g/m3 then, there is precipitation (that is why RH computed is over 100%). So that from 26.1g/m3 the water content will go down to 17g/m3... because the rest became water droplets. So he will end up with 100% RH with 17g/m3 at 20C???

Now the problem is that his instrument reads 55% so now I am lost..... unless... his instrument is calibrated only for a set temperature? Ken can you check the instruction manual?

Or maybe what we understand and read is all wrong....

However moving on Ken, as the others suggested just create other means of humidification. How does highlanders in the mountains get high humidity even with low temperature? My opinion only... precipitation in terms of fog and rain. :)

TTFN
Arvin

Re: Somthings really wrong..
 

Arvin, Thank you for your insights, which are used in the following calculation.

Assume that Ken was able to reduce the overall air temperature from 30 degrees C. to 10 degrees C.

At 30 degrees C. and 87% RH, the air holds 87% x 30 g/m3 = 26 g/m3 of water.

The air immediately adjacent to the ice bottle is at 0 degrees C., so at 100% RH, the air would hold 6 g/m3 of water, with the remaining 20 g/m3 of water condensing on the water bottle.

Assume that eventually all of the air at some time gets very close to the ice bottle, so all of the air would hold 6 g/m3 of water.

If the temperature of all of the air goes down to 10 degrees C. (with the exception of the small amount of air adjacent to the ice bottle that is at 0 degrees C.), the RH would be 6 g/m3 / 10 g/m3 x 100% = 60%, which is close to the 55% that Ken’s RH meter recorded.

Re: Somthings really wrong..
 

Okay as much as i appreciate all the rh thingy but 14 year old kid= O.o??? no idea...

Sooo arvin...Do you mean that when my temp goes down to 20C my RH should be 100%???? Im lost with the /m3 thingy

Just for info i can cool it down to around 15C-20C

Re: Somthings really wrong..
 

Ken, although Arvin and I have different perspectives of the reasons for your observations of reduced RH, we agree that the solution seems to revolve around the concept that warmer air can hold more water than cooler air.

When cool air gets warmer, RH is automatically reduced if no more water is added to it. The air in your terrarium is being cooled, but not uniformly. The air closest to the ice bottle is being cooled a lot, and the air farthest away from the ice bottle is not being cooled much. However, the air inside the terrarium moves, so the cooler air mixes with the warmer air, and there's an overall cooling effect.

When the humid warm air moves near the ice bottle, it becomes cooler and has to release water in the form of condensation. When the cool air moves away from the ice bottle, it warms up because it mixes with the warmer air. The RH is reduced because warmer air can hold more water than cooler air.

It's a continual process of humid warm air being cooled by the ice bottle, which eliminates water from the air, then warming up again, which reduces RH. The proof that water is being removed from the air is the condensation on the ice bottle. The ice bottle has a gemeral cooling effect on the air in the terrarium, but not enough to keep the RH high.

If you move the sensor of your RH meter near the ice bottle, I predict a higher RH, and if you move it far away from the ice bottle, I predice a lower RH.

Re: Somthings really wrong..
 

Hi jk...So if the surrounding cools naturally humidity wouldn't go down cos there is no no/not that much condensation compared to me putting a ice bottle in a terrarium where the condensation takes the vapour out of the air....Well i don't plant on getting any fancy gadjets sooo i'll just have to deal with the humidity....

Does adding more trays increase humidity in a cooled terrarium?? What i mean is does 2 trays make humidity higher than 1 tray or at 20C that certain amount of water is all it can take

I can mist my neps soo i guess that'll help out with the low humidity ( i think )

Re: Somthings really wrong..
 

Sorry i'm just bored and i still until now don't fully understand humidity/temp stuff....so lets say the temp at 20C, the maximum amount of water which the air is able to hold at that temp is around 60% (hygrometer) So if thats the max..Den in highland plants with percipitation and mist it wouldn't help with the humidity right?

Re: Somthings really wrong..
 

Er doesn't water droplets in the air condenses into cloud because low temp and more water condenses in the cloud make rain?If so ken's ice bottle (= low temp) make water droplets in the air turns into water on the bottle = not much water droplets in the air= lower humidity?

Re: Somthings really wrong..
 

I think the most importnt question is what CPs do you have in the terrarium, ken? And if they can survive under that relatively low humidity..? I think most nepenthes should have no problem.. what if you put a layer of moist sphag at the base of the terrarium?