The use of open bodies of water in
a vivarium has several benefits. The water helps maintain humidity in the
tank, especially if it is allowed to flow as a waterfall. The water also
acts as a heat sink, preventing rapid fluctuations of temperature within
the vivarium. It provides the inhabitants with a constant source of moisture,
and frogs will use it to deposit eggs or tadpoles.
One concern with combining water and false bottom
systems is stagnantation. Water that collects in the space under the drainage
layer can contain a lot of dissolved waste matter that might cause problems
if they are not dealt with in some way. To prevent this from happening,
a drain and sump can be installed in the vivarium to enable the water to
In this vivarium's case, a drain hole was drilled
in the lower right corner of the back of an old acrylic aquarium. A square
sided plastic jar is connected to the drain hole using a 1-inch plastic
bulkhead, to act as the sump. The higher the water flow that will be used,
the larger the bulkhead should be. The bulkhead has a strainer that slips
into the intake to prevent large objects from getting sucked in. Rubber
gaskets are used to make it watertight. The bulkhead is inserted through
the drain hole of the vivarium, into a hole drilled on the side of the sump.
The rubber gaskets are positioned between the flanges of the bulkhead and
the walls of the containers, one inside the vivarium and one inside the
sump. Make sure the bulkhead nut is screwed on tightly, to make the whole
system free of leaks.
A small water pump is placed in the sump,
and a plastic tube is used to direct the water to another, smaller bulkhead
with a barb fitting. This one is inserted through a hole higher up on the
back of the vivarium, where it will allow the water to flow from near the
top of the wall. The sump may be covered to limit evaporation if a notch
is cut in the lid to provide an opening for the water outlet tube and the
pump's electrical cord.
If an aquarium heater is to be used, it can be
placed either in the tank itself (but not in an inaccessible place like
under the false bottom-- you might have to adjust it one day) or in the
sump if the sump is big enough and in no danger of getting completely drained.
It is important that aquarium heaters always be kept constantly immersed,
otherwise they can overheat and crack.
At this point it would be a
good idea to test the system to see if everything is waterproof, before
anything else is added. The water level must be high enough so that
it easily flows through the bulkhead into the sump, and provide enough
volume in the sump so that the pump doesn't keep draining it dry.
In this vivarium, where a false bottom is used,
plastic eggcrate light diffuser is trimmed to fit into the bottom of the tank.
PVC pipe couplings are used to hold the eggcrate up to provide to drain space
beneath the eggcrate. Acrylic tabs are also cemented to the sides of the tank
for additional support. Even the bulkhead strainer lends some measure of support
for the eggcrate.
The eggcrate is cut to define the land areas, and
it is then temporarily removed. Coconut fiber matting is hot glued to the
sides of the tank, and the PVC coupling legs are also glued to the eggcrate.
The eggcrate is replaced, then perforated plastic WeedBlock material is used
to cover the eggcrate. A layer of more coconut fiber is put on top of this,
then fine orchid mix as added. In this vivarium's case, the drain is under
one of the eggcrate islands, where it will be kept safe from clogging because
the sides of the eggcrate platforms are covered with WeedBlock as well. Water
will then flow from sump pump to the outlet in the wall, down the coconut
fiber back, into a pool at the bottom of the tank, and through the fiber and
WeedBlock into the drain area, from which it flows through the bulkhead back
into the sump.
The flow of the water can be adjusted by partially
blocking the opening with coconut fiber. If the opening is kept completely
clear, the water jets out like a fountain, to splash into the pool below.
I prefer to block the opening a bit, which lets the water flow down and through
the coconut fiber. This keeps an area on the back wall wet, and the water
wicks around to provide a growing area for epiphytes that prefer a moist environment.
Allowing the water to flow down the fiber wall probably also allows bacteria
to process dissolved wastes, much like wet-dry filters do in aquariums. The
close contact of air and water enhances the action of bacteria that can break
down any ammonia and nitrites into less harmful nitrates, as well as keeps
the water well oxygenated.
Give the entire system a good rinsing with clean water, then
drain out and refill. Use clean plants that have been grown without the use
of pesticides or weed killers. Epiphytic plants
can be attached to the fiber walls. After a week or so to allow the system
to stabilize, animals can be added.