Humidity control 101

[SludgeMunkey]

Hello folks! Lately I have been getting quite a few messages from both anura and caudate enthusiasts about humidity control. this post will cover the entire concept in detail, from the physics and chemistry to the small scale user control many folks need. I hope that the more experienced users here will also put in their two cents worth as they are far more experienced in the keeping of anura than I am- I am a creepy salamander guy first and foremost!

Please utilize a search engine as you read, as while I will attempt to use laymen's terms for concepts as a guy with a heavy engineering background this can be a challenge for me.


Humidity Control 101

One: Understanding water basics:

Water covers roughly 71% of the earth in various forms. The liquid form of water is most predominant, followed next by water vapor (liquid water suspended in a gas) and then by ice, the solid form of water. While unrelated to this text, for reference the true gaseous form of water is steam, and is relatively rare in nature.

Water is comprised in its nominate form of two atoms of hydrogen with covalent bonds to one atom of oxygen. While by all appearances water is a very stable compound, in truth it easily and readily changes phase at "room temperature" (roughly 70°F, 21°C). Water is solid at 32°F(0°C )and boils at 212°F(100°C) -that is, it shifts from a liquid to a true gaseous state.

The water cycle is a complex system of the transferral of energy between states resulting in water shifting and circulating about the planet both terrestrialy and in the atmosphere by action of the addition of energy from the sun. While I could describe this for you in detail, I feel this is unnecessary as it has been covered many times before by authors superior in skill and knowledge to myself.

I highly suggest you read : The Water Cycle, from USGS Water Science for Schools as they lay it out pretty well. You need to understand this cycle in order to properly simulate it in a controlled environment like a pet enclosure.

Humidity is a measure of the amount of water vapor suspended in a gas such as air. It is best to use a search engine to read the details and understand the concepts as once again, more experienced individuals have covered this topic ad nauseum about the web.. I will not bother to write them out here for this reason.

[B Two: Know your Pet![/B]

It is impossible to post specific suggestions for humidity control in every enclosure in every climate for each species kept by every keeper in the world. My personal specialty is with caudates, temperate tree frogs and true toads.

You must (I say again) MUST! put forth the effort to read everything you can get on the species you keep or intend to keep. You are dooming your pet and yourself if you do not. In an age of instantaneous information there is no excuse not to be able to get such information on your own. Each species comes form different climates and, in the case of the same climate, inhabits different levels of the biome. It is the duty of the keeper to know and become familiar with such details. Keepers not interested in putting forth the effort should probably consider a goldfish or pet rock instead.

The first step in humidity control is knowing what climate you need to create fpr your animal!

<author steps outside to check on toads in their outdoor breeding enclosures during this storm....

Three: Enclosure, Enclosure, Enclosure!

No mater what aspect of amphibian keeping you are wondering about, the number one rule is :

BIGGER IS BETTER

That is, the bigger the enclosure, the better an environment you can provide. It is much easier to "control the weather' in a large volume as opposed to a small one. When keeping frogs and toads, there is absolutely no such thing as too big of a space.

When choosing an enclosure to buy or build you MUST plan in advance for the number of animals you intend to keep. Personally I feel that a volume of 20 US gallons each is the bare minimum for most arboreal frogs and ten US gallons for dart type frogs. Toads, pyxies, and other large critters need even more. For arboreal species, "up" is better. For terrestrial species "across" is better. that is, tree frogs need lots of height and terrestrial species need lots of ground area. Review the care sheets and forums here for species specific information. Scour the library and the web for even more.

When choosing enclosures for frogs and toads, especially tropical species, one must always keep ventilation in mind. ventilation is second only to volume when controlling humidity.

There is quite a bit of documented data on anura death as a result of poor ventilation. Yes, it is true, people have suffocated their pets to death because they did not do their homework. For tropical species this is most true, as they require environmental conditions well above the human comfort zone. People tend to have too little ventilation for these species in order to reduce evaporation and keeping humidity high.

For terrestrial species, I suggest a bare minimum of a ratio of 2:1 for temperate species and 1:1 for tropicals. (the first part of the ratio is actual surface area of the inside of the enclosure, the second is surface area of vents.

Remember that warm wet air rises, cool dry air sinks. An ideal frog enclosure has vents at both the base and the roof. this allows fresh air in and warm air out. This also helps control condensation which can lead to algae growth in high humidity enclosures.

For temperate, terrestrial species, I feel a full mesh top is sufficient if the base surface area of the enclosure is large enough. For arboreal species I feel ventilation should be a 50/50 mix between the base and top of the enclosure. Without proper airflow, you are creating a stagnant green house that will mold and stink. In some cases, the use of small fans may be needed to get good fresh air flow through an enclosure. In the case of tropical species, a heating source of some type is also required. the keeper must install the heat source in such a way to allow the warm air to circulate freely and eventually escape out the top of the enclosure, yet place it in such a way to prevent burns to the specimens. In the case of most tropical anura, a side mounted heat pad is ideal for this purpose.

[SludgeMunkey]

Four: Substrate, the secret to humidity control...

Once you have chosen or built a proper enclosure, you must choose an ideal substrate. For frogs and toads one must chose a substrate that holds moisture, yet resists becoming saturated and moldy. In many cases a simple substrate of a piece of indoor/outdoor carpeting is idea, as is various soils or coconut products. Not to toot my own horn, but I have two articles available on the web that cover this in detail. While written for caudates, most of this applies to frogs and toads too. They can be found here:

http://www.caudata.org/cc/articles/substrate1.shtml

http://www.caudata.org/cc/articles/substrate2.shtml

In the case of most frogs and toads humidity can be maintained by misting and/or a water dish of some sort. the keeper MUST invest in a hygrometer (thats a humidity gauge!) to keep tabs on the enclosure humidity. Daily inspection is a requirement. By knowing what humidity your pet requires, you can look at the gauge and add or withhold water as needed. In most cases, with a properly ventilated tank, daily misting is sufficient.

Many keepers spend time and money building "pretty" enclosures. As a self proclaimed vivaria expert I endorse such endeavors completely as long as they meet all the requirements for the health and safety of the animals involved. Most often, I see a lack of research and extremely poor choices in substrate in such enclosures that result in the death of the inhabitants.

FIVE: Water Sources

As stated before, daily misting is usually the best and most economical way to maintain humidity in a properly ventilated enclosure. This is highly dependent on the climate the owner resides in. Dry climates need to mist more often than wet climates. Ambient temperature also is a big factor, the warmer it is the more you need to keep tabs on enclosure humidity.

In dry climates especially, often the addition of a water dish or wet sponge to the enclosure is a necessary addition to help maintain humidity, especially in properly ventilated enclosures. In wet climates the use of small computer type fans may be needed to keep a proper evaporation ratio.
micro-climates can vary from house to house and from room to room. I can guarantee my basement critter room has very different temperature and humidity averages than say, someone's second story apartment.
As a result of this, water sources can range from the simple Tupperware container of tap water to elaborate pump/filter/fountain systems with spray bars, ultrasonic misters, and foggers. It is the duty of the owner to research, measure and adapt to their individual needs.

Truth be told, in most cases a spray bottle and a dish are extremely adequate if proper ventilation and temperature control are provided.