In a tropical terrarium, it’s important that the substrate does not become waterlogged. To prevent this from happening, a drainage layer should be created beneath the soil or other medium in which your plants grow. Gravel, LECA (lightweight expanded clay aggregate), lava rock, and foam packing peanuts are all common materials used for creating a drainage layer. A false bottom is yet another way to prevent the substrate in a terrarium from becoming fully saturated with water. False bottoms raise the substrate above the bottom of an enclosure using a perforated material through which water can flow. As water accumulates below, it can be siphoned out by pushing back substrate in a corner and placing a small hose through a piece of piping and into the water below. The main advantage to a false bottom is its light weight. For this reason, they are the ideal way to create a drainage layer in very large enclosures or in terrariums that may need to be moved in the future.
1 Inch (2.5cm) diameter PVC piping
Plastic light reflecting grid, a.k.a. egg crate
Foam rubber or polyfiber
Fiberglass window screen
Step One: Cut the PVC pipe into equal lengths. These will be the legs of the platform that supports the soil. 2 inches (5 cm) is normally long enough, but if an aquarium heater or pump will be placed below the false bottom then it may be best to use longer PVC legs to create a larger area below. In addition to these legs, cut one piece of PVC that is around 2 inches longer than the legs, cutting one end at an angle. For a standard 10 gallon aquariums that measure 20 inches long by 10 inches wide by 12 inches high (50 cm by 24 cm by 30 cm) I usually use five legs. If the aquarium is larger more legs will be needed to support the soil above.
Step Two: Measure and then cut the plastic fluorescent light grid so that it tightly fits inside the bottom of the aquarium. I use weed cutters or wire cutters to cut it. Scissors don't work well. Also, cut a small hole large enough to fit a piece of PVC pipe through in a corner of the grid.
Step Three: Place the PVC pipe legs in the bottom of the aquarium. Place one in every corner and then more in the middle or where needed.
Step Four: Put the plastic grid on top of the legs. This can be a little tricky because sometimes the legs tip over when you are placing the grid on top of them. It's even harder to do this when you are putting a water pump underneath to create a waterfall. Make sure the grid is on top of the legs and is not tilted.
Step Five: Place the extra piece of PVC pipe that is longer than the legs in the hole that is cut in the corner of the plastic grid. Make sure that the side of this pipe that was cut at an angle is facing the bottom of the tank. This pipe will be used as a drain so that when excess water builds up beneath the false bottom it can be siphoned out. A piece of foam rubber (available at fabric stores) or polyfiber (available in the fish department of pet stores) can be used to plug the top of the drain to prevent any curious animals from wondering down below. The photographs above do not show this drain because the tank that is photographed was only being used for several months, during which only a small amount of water built up below.
Step Six: Cut the window screen so that it is 1 inch (2.5 cm) longer than the light reflecting grid on all sides. Place the window screen so that it rests on top of the grid. This will keep soil from falling through the grid and into the water below.
You now have created a false bottom. It may be helpful to place a layer of orchid bark, fir bark, or coconut husk chunks on top of the window screen before adding soil to further help prevent soil from falling below the false bottom. There are many variations of false bottoms, this is just one way to do it. The technique that I use is based off of the way that the Arizona Dendrobate Ranch website shows.
Last updated 06.26.05
Building a False Bottom and Waterfall
Dendrobate Designs - False Bottoms
Setting Up a Vivarium