A Planned Bog Aquaria
- Freshwater microcosm plan
by glen-at-world.std.com (Glen W Osterhout) (Mon, 29 Aug 1994)
by glen-at-world.std.com (Glen W Osterhout)
Date: Mon, 29 Aug 1994
I have been operating my 75 gallon plant tank for almost a year now and,
thanks to the contributions of people here, it has been a great success.
I haven't had to buy plants for months now, I just take bunches of cuttings
to the store and trade for whatever I want. I'm now ready to try something
a bit more ambitious, and I would appreciate any feedback or comments you
might have. What I have in mind is a combination aquarium and bog tank
which is a self-sustaining freshwater microcosm, needing little more than
energy (in the form of lights and circulation) as input. This is my plan so
I plan to divide a 125 gallon tank into two sections with a plexiglass
partition. Water will spill over the top of this partition into the other
half (the boggy side) where it will be channeled through the roots of emersed
plants, ending up in a shallow pool (4-6" deep) from which it will be pumped
back over the partition by a plankton-friendly pump. The substrate on both
sides will be dug from a local pond or bog, and possibly placed over DIY
substrate heater coils. I plan to use as much pond water as I can transport
to start things, making up the difference with tap water. I will add plants
right away, and may introduce some invertebrates (such as Malaysian trumpet
snails or ghost shrimp) but I won't add any fish until the system reaches a
stable balance (I doubt that all of the New England pond life will be able to
adapt to the higher temperatures). In fact, the type of fish I add may be
partly determined by what kind of imbalances show up. For instance, if I get
a snail explosion I will add one or two snail-eating fish. I am hoping that
delaying the introduction of fish will also cause most fish parasites to die
off for lack of a host. The bog side will probably remain fishless, and will
serve as a refugium for plankton. I have never attempted a bog tank, so any
advice on that aspect would be much appreciated.
Some gory details:
The Divider Partition:
The first problem is how to keep the partition in place with the weight of
water pressing against it from one side. I plan to buy some plastic or acrylic
doweling (1/2" thick ) and glue a piece along the top/front, bottom/front,
top/back and bottom/back inside edges of the tank, so that one end of each
dowel rests against the frame and the other rests against one corner of the
partition. This should stop it from sliding. I think 1/2" thick plexiglass
sheet should be enough to prevent bowing. I will use silicon cement to provide
a waterproof seal, and I hope it will stretch enough to keep a seal when the
glass walls of the tank flex when water is added.
I will probably use 6 40 watt fluorescent bulbs which will cover all of the bog
end and half of the aquarium end, with a 175 watt metal halide pendant
covering the other half.
This is the tricky part. The idea is to gently lift water from the 4-5" deep
bog end of the tank over a 20" high partition, without mangling all the nice
plankton that I hope to be growing. There are no plankton-friendly pumps on
the market as far as I know, so I will have to try to build one myself. Some
Archimedes screw - size and angle necessary is awkward and hard to make
Air lift - noisy, may not work very well lifting water from the shallow
depth in my bog setup.
Bilge type piston pump - I think this is the best-suited, but building
one is a fairly ambitious goal. Maybe I can find something suitable in
a boating supply store (a small bailer for instance). I have some ideas
about how to build one, but I'm afraid it would end up looking like
some 19th-century-factory belts-hanging-from-the-ceiling-OSHA-nightmare.
Venturi effect - this works the same way as water changers such as the
Python, but I would use a power head instead of tap water pressure to
create the suction. The power head would just pull water from the main
part of the aquarium in through a sponge filter and release it back into
the same area, so I would need a pump with a high flow rate but not one
with much head. The venturi suction would then be used to lift water from
the bog side into the main part of the tank. This is easy to build, and
is what I will most likely use.
I don't think the uneven strain caused by putting in the partition will
create a dangerous situation. Has anybody ever done this? I know the river
tank systems have similar dividers, but not in such a large aquarium.
I know I am breaking the rules about having organic materials in the
substrate, but Adey says it will work. If he's wrong, I'll probably end up
with a hydrogen sulfide factory.
I would guess that the biggest potential problem is that of trying to adapt
New England pond life to a tropical environment. I wish I lived somewhere
further south, but I don't see any field trips to the Amazon in the near
future. The little research I've done on North American pond life hasn't
told me much about the temperature ranges required.
Well, that was a long post. I don't know if anybody else is interested in
this sort of thing. Let me know if you have any comments.