Somthings really wrong..
 

Hi guys.......Well i placed a tray in my terrarium and i manage to get humidity up to the high 80's but something is seriously wrong here.....Whenever i start cooling down the terrarium with ice bottles the humidity immediately drops a lot.......Sooo what "science" am i missing here:spinning::confused: What does cooling have to do with reducing humidity....At first i thought maybe its just a coincidence that the humidity drop the time i placed the bottle in but then i tried it out a few times and SAME results!!!! Once it even when as low as the 30's

Heres a picture when there is no ice bottles
http://i297.photobucket.com/albums/m...s/RIMG2384.jpg

With ice bottles..Sorry for this blur pic...Anyways the it shows the humidity is 55%
http://i297.photobucket.com/albums/m...s/RIMG2383.jpg

Please help....:sweating::mad:

Re: Somthings really wrong..
 

Is there condensate on the bottle. Lots of it and the lid of your terrarium is only partially open (mostly closed)? Why not leave the bottle there till all the ice melts and at the same time note the humidity every 5 minutes. See whether the humidity drops when the bottle has condensate and after all the ice melts hence very little or no condensate whether the humidity picks up.

Re: Somthings really wrong..
 

Hi bactrus..condensate you mean by droplets of water on the bottle right?? And yes there is droplets...I shut the terr fully tight to try to keep humidity...I don't really get some of the stuff like

Re: Somthings really wrong..
 

1. Take a couple of readings with terrarium closed before placing ice.
2. Take a reading outside terrarium also as control.
3. Insert ice bottle then shut the terrarium.
4. Take reading every 5 minutes till ice melts and water returns to room tempreture.

My two cents worth.

Re: Somthings really wrong..
 

Hi...

1.take readings while terrarium is closed without bottles = Done/humidity 80+%
2.take outside terrarium= Done/humidity 50-60


I was thinking could it be that since the cover was closed and i opened it to place the ice bottles in the humidity that was traped inside was lost???? But then again if humidity does go lower it should come back up after awhile since i shut the terrarium again... BA It takes a couple of hours before the whole ice bottle turns water and becomes room temperature LOL.....Anyways i'll try..

Re: Somthings really wrong..
 

This afternoon i tried putting in 1 ice bottle and from 80+ humidity it went down to 50+ (usual thingy) So after 6 hours im back from school and humidity was around 60's and the bottle has melted and tuurned room temperature...I took it out and cover the terrarium again and humidity went up to 80+ in about 10 mins.....Whats wrong!! LOL......Could it be that the cold temp affects my hygrometer??????

Re: Somthings really wrong..
 

Hey Nice, you have found it out yourself, I didn't know this too but I did some googling and found the following information from this site: http://archive.amol.org.au/recollect...f/humidity.pdf.


"Relative humidity is a measure of the amount of water-vapour contained in air at a
particular temperature. It is basically a comparison between:
•the amount of water-vapour held in the air at any one time and at a particular temperature; and
•the total amount of water-vapour which the air can hold at the same temperature, that is,
the amount of water which will saturate the air at that temperature.

Relative humidity is expressed as a percentage.
This can be written as an equation:
RH = water-vapour present in the air x 100%
water-vapour required to saturate air at that temperature
As the temperature of air increases, its capacity to contain water-vapour increases. For example:

•At 0ºC the air can hold about 6 grams of waterfor each cubic metre of air, that is, 6g/m
•At 10ºC this increases to 10g/m3
•At 20ºC it increases to 17g/m3
•And at 30ºC it increases to 30g/m3

So, if air at 20ºC contains 8.5g/m3
of water-vapour:
RH = 8.5 x100%
17= 50% "

So there you go, the answer is that the RH has changed when you cooled the air because the temperature went down and so the water holding capacity of cold air went down!

Where did it go? My guess is that the excess water that the air can't hold has pricipitated into dew (water droplets).

Now we know and knowing is half the battle! I'm glad that you made me check it out. :)

Re: Somthings really wrong..
 

Arvin, Extending your example, if the air at 20 degrees C. with 8.5 g./m3 were cooled to 10 degrees C., RH would increase from 50%, as you calculate, to 8.5 x 100% / 10 g./m3 = 85%. That's assuming that the air holds the same amount of water. Some water must be coming out of the air when cooled for RH to drop.

Re: Somthings really wrong..
 

Ken, I think you fill up yours terrarium with water. Full or half cover the terrarium. And try it. I believe the huminity will be better. Just 2cent. (reply yours thread with rush and didnt read what others reply.)

Re: Somthings really wrong..
 

Hi Arvin/jk

Thanks for the reply....Though i might not understand some of it but does this mean basically when the temperature goes down the amount of water the air can hold drops? And if so how do i actually bring humidity up but still maintaining the temperature

Casey

I have a tray in the terrarium already but does this mean i have to add more???



One thing..So how does highland plant get high humidity at night (in the wild) Mist??

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?

Re: Somthings really wrong..
 

Oh yea 1Q since paphio mention LFS.. Will it make much difference if i put Moist LFS at the base of the terrarium rather than a tray of water??? Will humidity be reduced or increased???

Paphio,
I haven't start this terrarium yet as i want to know more about stuff like this before i really start :)

Oh yea if i start this i think'll ill try with my ventrata cuttings and other more umm easy neps 1st...

Oh almost forgotten.....How much air circulation does a nep need?? I read somewhere in the forum that neps need less airflow compared to dews... So can anyone Define the amount of air flow needed???

Re: Somthings really wrong..
 

ken, I have to ask you.. what is the main purpose of your terrarium? Is it to grow highlanders only? Or do you intend to create a display case of lowlanders (in which case, you don't need cooling).. I think ventrata is a good candidate to check your airflow and humidity. If too much humidity and little airflow, might develop fungal problems and die. You might want to try a few cuttings of amp, if got any to spare and bical, as these 2 ake quite boggy conditions...

Re: Somthings really wrong..
 

I might try a highland terrairum with a ice bottle in a cloed terrarium....As for humidity maybe i shall get myself does small machine which makes a misty cloud right over the waters surface..I read somewhere that it'll make humidity to 100%

Or i will just make a high humidity tank which will help me out with some finicky highland neps

Re: Somthings really wrong..
 

Just wanna give it a try on the question, but most porably it won't help much, since it already pass that long..hehe
As i know, in order for the water droplet to form around the cold media(ice bottle) there need water vapour or any state of water that exist in our atmosphere, as water vapour absorb the cold, the hydrogen bonds form between water molecules and hence stick to the cold water bottle, so far anyone who read this should be understand..hehe, a bit scientific word.
Then, water droplet form at the bottle, but during this process, the humidity will be lower, it is because the percentage of the water vapour in the atmosphere is directly inversely to the amount of water vapour, as water is form, which means the water vapour in the atmosphere had changed it's form from water vapour to water droplet, and this will cause drop in the humidity.....the humidity remains till so low because the transpiration of plants and water still evaporate but it had reach a stable condition at that level, thats why it state the humidity level on twenty something, this process continue until the temperature of the ice reach a point when less water vapour is converted to water droplet and then the humidity increases the "converting" process begin to slow down and return back to normal level as the converting process not that vigorous....
(pls-this is just theory, possible to wrong in any description, do correct me...)
Anyone agree with this?