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Dave Jay

Well-Known Member
1,000+ Post Club
I use false bottoms in enclosures requiring many different conditions but I find they are at their most beneficial when keeping arid or desert animals.
It allows you to keep the surface mostly dry, avoiding mycosis and other problems associated with a higher than desirable humidity/moisture level yet the animal can seek moisture if needed.

Looking at the pictures you can see that a wide variety of moisture levels are available to the animal negating the need for the keeper to provide a certain humidity or moisture level. It also negates the need for constant vigilance by the keeper, the animal will simply dig deeper as the substrate dries out. So going on a holiday is less stressful, adding extra water before leaving does not result in the animal being in unsuitable conditions, it simply moves to a higher point in the substrate, as the surface dries it can follow the moisture down again or take advantage of moisture trapped by cover.

You can see that in the pictures there are a few pebbles on the surface, this is because the substrate had dried out more quickly than those around it during a lax in care and the spider followed the moisture down to the very bottom, had I not used a false bottom system there is a high probability that this spider would have died.
In larger enclosures I add a layer of straight peat over the pebbles, all I need do is to keep the peat layer damp and the gradient will form. If I see the colour of the peat lighten, or see peat at the surface I know it is time to add more water. Of course you don't wait for that each time, but it helps you get a feel of how much water is needed and at what intervals so you can fine tune your routine.

Surprisingly little water is needed to maintain the gradient and with large enclosures water might only need to be added every couple of months. Smaller enclosures may need water more often, I find it convenient to add a small measured amount of water fortnightly when feeding, but even a small enclosure will last one or two months without ill effects to the occupant in most cases.

One big advantages are that you don't need to maintain a particular humidity or moisture level yourself, a wide range is open to the animal, it can vary the levels it'self to suit it's needs at any given time or stage of development. If it needs to go into ecdysis or hibernation/brumation/diapause etc it can find the perfect conditions for it'self without any guesswork on the keepers behalf at all.

Another advantage in relation to keeping arid or desert species is that with other set-ups you are often relying on a water dish being filled or an area being misted to avoid the animal becoming desiccated, with this method there is a large moisture reserve, most animals from dry conditions have ways to avoid desiccation, they will burrow or hide under cover where the moisture levels are higher.

Even animals that don't burrow will still benefit from a false bottom system, any cover, be it solid cover, loose or layered material traps the moisture from below at the substrates surface. So even though the exposed substrate is dry, under a rock, piece of wood etc a higher moisture level can be found.
With loose material such as leaf litter, sphagnum moss or similar the moisture will vary, with the higher levels being found deeper into the pile, closer to the substrates' surface, conditions that most desert animals are adapted to seek out should the humidity be too low.
Often applying water from above results in the areas under cover being wetter on top and drier underneath, the opposite of natural desert conditions (excluding brief periods directly after rainfall).

To set up these enclosures I have added a layer of small smooth surfaced aquarium pebbles, this layer is to allow the water to spread across the bottom of the enclosure more evenly before being taken up by the substrate.
A larger enclosure will allow for a larger sized gravel or medium to be used. People often use marbles or expanded clay hydroponic or aquarium filter balls. Where the animal is likely to come into contact with the medium it is wise to use something rounded for safetys' sake I think.

This layer can be topped by a piece of mesh, fabric, shade-cloth etc, or by a rigid structure such as perforated acrylic, a light diffuser grid or something similar that allows for water transfer. This is to stop the medium becoming clogged with substrate and in some cases to stop the animal from reaching the bottom layer.

Because I was housing tarantulas I opted to not have a divider between the gravel and the substrate, the majority of my enclosures for tarantulas have a rigid divider or none. With other inverts I often use plastic fly screen mesh.

I then stood a straw that has the bottom cut at an angle and punctured in the corner. This is to add water, I use a syringe to do this when a straw is used.
For larger enclosures you would ideally use food grade hose or pipe but irrigation hose is often used. In my 4' frog enclosure I have used a small orange juice bottle with holes around the bottom because of the screw top lid and the amount of water added at one time.

For these little ones I just added the substrate mix directly onto the gravel, adding it a tablespoon at a time ,compacting it as I add it. When I near the depth I want some decor is added and substrate compacted around it, that way everything is stable and embedded firmly into the substrate.
In larger enclosures I will add a layer of straight peat over the gravel or mesh/divider ,compacting it to between 1cm and 1 inch depending on size before adding the actual substrate.

I took these pictures recently and they illustrate the advantage of a false bottom system. The substrate is one part sand to 6 parts coir peat by volume. This is still a very sandy mix really, this is what I use for most of my inverts, it is very similar to sandy soil found in the Australian Bush. I often hear 1:1 mixes being advised but by volume that is very sandy, it may result in a mix similar to mine if measured by weight, I haven't tested it.
I find that a mix is better for judging moisture levels by eye than straight sand or straight peat is, these pictures show that well I think.

The substrate in the enclosures is the same from top to bottom, the colour graduation is purely because of the moisture gradient created. As you can see many different moisture levels are available, there is a clear horizontal moisture gradient (bottom to top) and to some extent a vertical moisture gradient too (front to back). The surface also provides a variety of moisture levels, the sphagnum moss tying in with the vertical gradient dictated by the placement of the straw.

The tarantula species housed in these particular enclosures is Selenotypus "sp. 2", an arid Australian species.
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Dave Jay

Well-Known Member
1,000+ Post Club
A few phone pictures of some of my scorpion enclosures housing burrowing desert species.
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With these enclosures no water is ever added to the surface at all, water is added from the bottom, just enough to stop the layer of peat at the base drying out. In one of the pictures you can see that the peat in one enclosure is lighter than the others, I will add 10ml of distilled water when I feed next and that will be all for at least a month. Although, except for directly above the peat the sand would feel dry to us if I were to tip it out (chip it out more likely, it's like cement!), the moisture from the peat is working it's way up in degrees that a desert animal can detect. The depth of the burrow and then the position of the animal in the burrow allow the animal to find the perfect humidity at any one time, when a higher humidity is wanted, perhaps for moulting or brumation/hibernation/diapause the burrow is blocked by the animal to raise humidity.

Although these enclosures house scorpions the principle can be used when housing any moisture sensitive desert animal.
 
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Mr. P

Well-Known Member
I do this for the ones that need a little more humidity. Instead of using standard pebbles/rocks which only displace water I use clay balls which absorb the water and releases it more slowly over time. The slow and steady release keeps the hunidity more constant and prevents it fluctuating up and down as the water is added and evaporates.

I know there are some out there who say you shouldn't even worry about the humidty and for the most part I don't, but you do have to consider it. Some T's do come from some very wet places on earth and are just more comfortable with it then others.
 

Dave Jay

Well-Known Member
1,000+ Post Club
I do this for the ones that need a little more humidity. Instead of using standard pebbles/rocks which only displace water I use clay balls which absorb the water and releases it more slowly over time. The slow and steady release keeps the hunidity more constant and prevents it fluctuating up and down as the water is added and evaporates.

I know there are some out there who say you shouldn't even worry about the humidty and for the most part I don't, but you do have to consider it. Some T's do come from some very wet places on earth and are just more comfortable with it then others.
Humidity itself is a measure of the amount of moisture in the air which will vary depending on the humidity in your home and the temperature at the time, trying to maintain a certain number is futile really. To a certain extent it can be raised or lowered by varying the amount of available moisture present and by adjusting the ventilation, you are limited by the ambient relative humidity in your home and by the temperature though so it will always vary no matter how often you make adjustments. What you're taking readings of is the relative humidity of the air in the enclosure, it doesn't really reflect the humidity in a burrow. With a false bottom you usually have as much ventilation as possible and the animal adjusts the burrows humidity by varying the depth of the burrow and it's position in it, the ambient relative humidity in the enclosure has little influence on the depths of the burrow unless it's very extreme. For this reason I like to use a false bottom for animals that suffer if the humidity is too high, the surface and most of the substrate is dry but they can follow their natural instincts and burrow deeper if they require a higher humidity in the burrow or sit higher in the burrow or on the surface when they don't.

Like you though, I also use it for animals requiring a high moisture/humidity level, adding water to the bottom is better than flooding the top all the time which gives the animal no choice at all and promotes fungal and mould problems.
 

Jess S

Well-Known Member
Hi @Dave Jay

Really informative, thanks. So the ''false bottom" is the gravel or clay ball layer that holds the moisture which you pour directly to the bottom?

If I've understood this right, a false bottom setup could also serve well a dryer terrestrial species, because it gives it the option to dig down to find a more comfortable, cooler humidity level, while still enjoying the dryness at the top? Like the best of both worlds.

You also say this method can lessen the explosion of mould (I assume that's as long as there's plenty of ventilation).

I'm sure I've heard other people talk about this, but your explanation really helped it 'click' in my mind. So, thank you. And please feel free to correct me on anything I've asked above, if I've got any of it wrong.

One other thing was, does anyone have any gravel or clay ball brands to recommend?
 

Dave Jay

Well-Known Member
1,000+ Post Club
Hi @Dave Jay

Really informative, thanks. So the ''false bottom" is the gravel or clay ball layer that holds the moisture which you pour directly to the bottom?

If I've understood this right, a false bottom setup could also serve well a dryer terrestrial species, because it gives it the option to dig down to find a more comfortable, cooler humidity level, while still enjoying the dryness at the top? Like the best of both worlds.

You also say this method can lessen the explosion of mould (I assume that's as long as there's plenty of ventilation).

I'm sure I've heard other people talk about this, but your explanation really helped it 'click' in my mind. So, thank you. And please feel free to correct me on anything I've asked above, if I've got any of it wrong.

One other thing was, does anyone have any gravel or clay ball brands to recommend?
Yes, you have grasped the concept completely, it's when keeping desert animals that you get the most advantage but it's an easy way to keep most animals at their desired moisture levels, not to mention that you can go on holiday for a month or so and not worry that enclosures will dry out. You're right about mould too, the only time I get any is when I spray an enclosure.
 

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