Top/side ventilation from the view of molecular motion

[EulersK]

The isos and springs aren't perfect garbage disposals but I havnt had mold problems since I've heavily included them in my enclosures.

I really need to look into these. I'm getting sick and tired of mold outbreaks.

 

[viper69]

It depends on the species and the set up. I have an H.mac who is kept in a ten gallon on about 10" of top soil, peat, and sand. Her tank is also heavily planted. I added powder blue isos (p prainosus), giant canyon isos, and tropical springtails over a year ago and you can still turn over oak leaves in the tank and find them scurrying around.

In some of my small tanks which dry out more frequently, I will see food bulbouses and poop start to accumulate so ill go over to my spring colony, take a big oak leaf from the colony, and flick it into the desired enclosure.

The isos and springs aren't perfect garbage disposals but I havnt had mold problems since I've heavily included them in my enclosures.

Thanks, there are so many vendors for these insects. PM me if you have a favorite or some you DON'T recommend.

 

[Bugmom]

I haven't had that problem at all. In fact, peat moss is the only thing I can use that holds on to moisture for long periods of time. Are you sure you're using peat moss? The proper term is sphagnum moss - does other say that on the bag?

I haven't bought any in years, but it was definitely peat moss. I remember buying it for plants and having the problem of the water not draining down into the roots.

 

[sschind]

I haven't bought any in years, but it was definitely peat moss. I remember buying it for plants and having the problem of the water not draining down into the roots.

My experience is that if you let peat moss (and to a lesser extent cocofiber) dry out completely you will get what you describe (water just pooling rather than absorbing or water sinking to the bottom and the peat floating) for a little while until it can soak in. If you wet the peat first by pouring in some water and then squishing it around in your hands then it will readily absorb and hold subsequent water as long as you don't let it completely dry out. I'm not sure of the reason for this but my guess is that the peat particles are so light and the surface tension of the water is so high it takes a long time for them to actually interact and not just have the peat float on top. Once the peat is damp though it changes things quite a bit.

 

[BobBarley]

I really need to look into these. I'm getting sick and tired of mold outbreaks.

A local species of springtails decided to move in several months ago and I have since perpetrated the species by spreading them to all of my moist enclosures. They work wonderfully and I almost never see mold, even in low ventilation, high humidity enclosures. They also make it easier to find blouses that blend in with the sub because they swarm over the blouses and they shine and sort of reflect light. Pretty helpful little guys and I think I may buy some of those "giant springtails", the scientific name is slipping me at the moment. Anyway, springtails work great.

 

[EulersK]

A local species of springtails decided to move in several months ago and I have since perpetrated the species by spreading them to all of my moist enclosures. They work wonderfully and I almost never see mold, even in low ventilation, high humidity enclosures. They also make it easier to find blouses that blend in with the sub because they swarm over the blouses and they shine and sort of reflect light. Pretty helpful little guys and I think I may buy some of those "giant springtails", the scientific name is slipping me at the moment. Anyway, springtails work great.

This needs to happen. I'm getting really sick of constantly cleaning up mold, and I'm sure my spider's aren't too fond of it either.

 

[viper69]

This needs to happen. I'm getting really sick of constantly cleaning up mold, and I'm sure my spider's aren't too fond of it either.

 

[EulersK]

Fun fact: This plays every hour, on the hour when you leave the city limits. No one knows why.

Speaking of, I actually did end up doing that mold test we spoke of awhile back. No issues to speak of.

 

[viper69]

OH you tested, and no mold..cool

 

[EulersK]

OH you tested, and no mold..cool

Well, to be more precise, I tested the rest of the house with no significant results. My T room was... pretty bad. Which is honestly to be expected. I'm was going to invest in an air purifier, but I'm going to run with these isopods for a few months and then run the test again. Perhaps those little buggers are what I've needed all along.

 

[viper69]

Well, to be more precise, I tested the rest of the house with no significant results. My T room was... pretty bad. Which is honestly to be expected. I'm was going to invest in an air purifier, but I'm going to run with these isopods for a few months and then run the test again. Perhaps those little buggers are what I've needed all along.

OHH, keep me posted.

 

[Trenor]

I have a B.S in chemistry and a minor in physics. I spent a year studying thermodynamics and particle motion and I will tell you that from our modern understanding of particle motion top ventilation will let out just as much moisture as side ventilation.

Liquid water evaporates when enough energy is transferred into the water molecules to break the attractive forces the water exerts on itself. The newly freed water vapor is going to exert uniform pressure on all sides of the container and will be equally likely to escape through any side if all sides are the same size.

The only things that are going to effect tank humidity will be.... the number and size of the holes present, air movement against the container (dry air will essentially steal moisture from wet air), and the temperature at which the container is kept.

Do not think that punching only holes on the sides will give you superior ventilation than only poking holes on the top or vice-versa.

I know this thread is old but I've get a few questions.

How will a temperature gradient in the room (my floor temp can be 8-10 degrees cooler than my ceiling temp) affect the evaporation in an enclosure?

Right now the room is very dry from the heater. I don't have a fan moving air right now which is why I have such a temp gradient.

I made two deli cups into test enclosures. Using the same soldiering iron I put 4 holes around the side of one cup and 3 around the side and 1 on top of the other cup. I added water to the bottom of both cups (about 2 inches deep). I got slight condensation build up on the one without the top hole and none on the other. Could this be because of the temp gradient in the room? They were also on the side of the room with the heater too so this could have come into play as well.

In the above test, I think if I add a few more holes to both, it wouldn't have been an issue either way but with just a few it was. Also, we are not likely to add that much water to an enclosure with a T in it.

I was just wondering about the results.

 

[HybridReplicate]

I know this thread is old but I've get a few questions.

How will a temperature gradient in the room (my floor temp can be 8-10 degrees cooler than my ceiling temp) affect the evaporation in an enclosure?

Right now the room is very dry from the heater. I don't have a fan moving air right now which is why I have such a temp gradient.

I made two deli cups into test enclosures. Using the same soldiering iron I put 4 holes around the side of one cup and 3 around the side and 1 on top of the other cup. I added water to the bottom of both cups (about 2 inches deep). I got slight condensation build up on the one without the top hole and none on the other. Could this be because of the temp gradient in the room? They were also on the side of the room with the heater too so this could have come into play as well.

In the above test, I think if I add a few more holes to both, it wouldn't have been an issue either way but with just a few it was. Also, we are not likely to add that much water to an enclosure with a T in it.

I was just wondering about the results.

I haven't tested this systematically, but I have a few display cases I have modified for enclosures. Those that only have cross ventilation or top ventilation tend to fog up if the substrate is too damp. Those with both cross & top ventilation seldom fog up & dry more quickly.

I always assumed this was due to warmer air rising out the top while cooler air is permitted to enter from the sides.

 

[Jeff23]

I am not sure that I buy into the idea that top ventilation and side ventilation are the same. I am an engineer, but that is in electrical which is not similar to this area.

Let's suppose we have two small enclosures. One has side ventilation and a second one has top ventilation sitting side by side. Now we open a door to this room or any room that creates air flow in the room. Or perhaps we just walk through the room where our body creates an air draft. The enclosure with the side vents is going to get much more air flow in my mind. More air flow WILL dry out the enclosure faster.

This is not different from you standing in a valley where you don't feel any air flow versus the top of the hill where you feel a huge breeze blowing. I think they are only the same if we are talking about a laboratory system where no outside forces are involved.

 

[Trenor]

This is not different from you standing in a valley where you don't feel any air flow versus the top of the hill where you feel a huge breeze blowing. I think they are only the same if we are talking about a laboratory system where no outside forces are involved.

See this was my thoughts too. In the video with the drop, I image they had the drop in an enclosed heating environment (fancy way to say oven ). Since the heat was consent from all sides the distribution was the water particles were same. If there was more heat from below than above would the movement of the heat cause more water particles to be pushed up with the heat? Which is why I asked about the heat gradient. I image air movement would be similar as well. More of the water particles would be moved in the direction of the flow of either of these.

 

[Jeff23]

See this was my thoughts too. In the video with the drop, I image they had the drop in an enclosed heating environment (fancy way to say oven ). Since the heat was consent from all sides the distribution was the water particles were same. If there was more heat from below than above would the movement of the heat cause more water particles to be pushed up with the heat? Which is why I asked about the heat gradient. I image air movement would be similar as well. More of the water particles would be moved in the direction of the flow of either of these.

I think I got over-powered with my thought about the OP's post and obsessed about air flow, but I agree with you. I don't see the heat gradient being that different from the bottom of an enclosure to the top. But I could see the humidity having a gradient for our species that need moist substrate.

Of course I am certainly not an expert and very interested and willing to better understand the science on it.

 

[Abyss]

Great read, very good info here!!!

 

[z32upgrader]

Great info, thank you!
I do have a question, though. It's been a common myth on these forums that humid air rises, so top ventilation will lead to moisture immediately being lost. I've never bought this for two reasons. Firstly, energy has to be invested into liquid water for it to evaporate, meaning the resulting humid air is slightly cooler than surrounding air. Since cool air sinks, would it not just stay at the bottom of the enclosure? Further, humid air is also slightly heavier than dry air, once again leading it to settle at the bottom. These are both assuming that there is no turbulence present, I understand that, but is what I'm saying generally true? And if so, wouldn't air holes at the very bottom of the enclosure result in much more moisture lost than anywhere else?

I'd like to correct @EulersK about the supposed myth that humid air is less dense than dry air. That is exactly the case! Using Avogadro's Law, where "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules", the weight of a gas and therefore its density relative to other gasses is determined by the atomic mass. For instance, O2, has an atomic mass of 32, 16 for each Oxygen atom. Water vapor H2O has an atomic mass of only 18 with Hydrogen's atomic mass of (1) (x2) + a single Oxygen atom (16). Helium balloons and natural gas are good examples of this Law. Helium has an atomic mass of 4 and balloon full of helium (and at much higher pressure as well) in the atmosphere full of N2 and O2 is so much lighter and therefore rises. Alternatively you can take a lighter and hold the button down pointing at the mouth of a cup and the gas will collect there in the bottom because it is heavier. It will stay there in the bottom of the cup for a while until you finally light it.
Conclusion:
Water vapor is lighter than Oxygen and Nitrogen, and in accordance with Avogadro's Law will make the whole air mixture lighter than dry air (just O2 and N2) that might be entering the enclosure from a draft, displacing the humid air and forcing it to rise up and out of the enclosure.

Also the idea that "energy has to be invested into liquid water for it to evaporate, meaning the resulting humid air is slightly cooler than surrounding air " is completely false.
Liquid water will evaporate without any additional heat applied. Ever left just washed dishes in the drying rack? It doesn't all drip off. The little pool of water sitting on the bottom of your upside down coffee cup still evaporates.
As water evaporates it takes heat with it as it changes state, the whole reason you sweat, and why your sweat cools you off. The water gains heat from your skin as it evaporates, it doesn't become cooler.

 

[EulersK]

I'd like to correct @EulersK about the supposed myth that humid air is less dense than dry air. That is exactly the case! Using Avogadro's Law, where "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules", the weight of a gas and therefore its density relative to other gasses is determined by the atomic mass. For instance, O2, has an atomic mass of 32, 16 for each Oxygen atom. Water vapor H2O has an atomic mass of only 18 with Hydrogen's atomic mass of (1) (x2) + a single Oxygen atom (16). Helium balloons and natural gas are good examples of this Law. Helium has an atomic mass of 4 and balloon full of helium (and at much higher pressure as well) in the atmosphere full of N2 and O2 is so much lighter and therefore rises. Alternatively you can take a lighter and hold the button down pointing at the mouth of a cup and the gas will collect there in the bottom because it is heavier. It will stay there in the bottom of the cup for a while until you finally light it.
Conclusion:
Water vapor is lighter than Oxygen and Nitrogen, and in accordance with Avogadro's Law will make the whole air mixture lighter than dry air (just O2 and N2) that might be entering the enclosure from a draft, displacing the humid air and forcing it to rise up and out of the enclosure.

Also the idea that "energy has to be invested into liquid water for it to evaporate, meaning the resulting humid air is slightly cooler than surrounding air " is completely false.
Liquid water will evaporate without any additional heat applied. Ever left just washed dishes in the drying rack? It doesn't all drip off. The little pool of water sitting on the bottom of your upside down coffee cup still evaporates.
As water evaporates it takes heat with it as it changes state, the whole reason you sweat, and why your sweat cools you off. The water gains heat from your skin as it evaporates, it doesn't become cooler.

I'm nothing but an armchair theorist. Seems like your issue lies more with @woodermeloon, as just about everything you said contradicts what he said I'm no physicist, not even close.

 

[Jeff23]

I'm nothing but an armchair theorist. Seems like your issue lies more with @woodermeloon, as just about everything you said contradicts what he said I'm no physicist, not even close.

Same with me. While I understand how an air draft affects things from real life experience, I don't have enough time on my hands to study particle physics.

But it definitely makes sense to me that the air would be more stagnant without cross ventilation. Unless you have some kind of down drafts entering the top vents the process would be slower. In this case lack of turbulence will slow down any large differences in the liquid water becoming gas versus gas water becoming liquid (based on relative humidity at the surface).

Another thing to ponder is that we are initially talking about the volume of liquid at the surface of the substrate which means the evaporation may start at a higher rate. But as this surface area dries the liquid is more dense below a portion of the substrate. So I must wonder if the volume of other particles will also slow down the evaporation since we now have less water coming into contact with air. Once again it seems like some type of turbulence in the air will speed up this process.