The bigger the tank, the more water it holds, the more water, the
more fish, the more fish, the cooler the tank! The more fish, the more
fertilizer, the more plants you can grow.
The general
consensus for the number of fish a tank can hold is 1 inch of fish per
gallon of water. This means that a 10 gallon tank can hold 10 inches of
fish, nose to tail. Goldfish are 3-4 inches long, so a 10 gallon
aquarium can hold 3 goldfish. This is kinda boring, having so few fish
in a tank. So everybody I've ever seen breaks this rule of thumb, and
overstocks their tank. But I digress...
Small Aquariums
I
consider any tank or fish bowl under 10 gallons a small aquarium. They
can be a lot of trouble, as generally the fish just don't seem to live
as long and are prone to massive die-outs when compared to larger tanks.
They have to be regularly maintained, as 'letting it go' for a few days
on a very small tank like 1 gallon, can have disastrous consequences.
They can go from just fine to sick in a matter of hours. The filter
systems for these tanks are limited as there isn't much room in the tank
for an internal filter, and not much room to hang an over-the-side
filter on. External canister filters don't work well here as they are
either way to big, or are so weak that they are prone to plug up.
Lighting can be challenging, with even the small wattage bulbs causing
the water to heat excessively.
Adding a hydroponic
component to tanks this small usually means doing something as simple as
setting a Peace Plant into the tank. You can also suspend plants over
the top of the tank in a Static Solution Culture type system where you
take advantage of the aeration bubbles at the top of the tank. If your
tank is on the larger size of this size bracket, you may be able to do
something like aeroponics or a Nutrient Film Technique if you use a
small channel and short, thin hoses. Remember, you don't want to pump
much water out of tanks this small as the water level drops quickly. If
you top the water off on the tank so it looks good while there is water
outside of the tank in they hydroponics system, and the power goes out, a
tank overflow is an easy result.
The big benefit to
adding hydroponics to a very small system like this is that when used in
conjunction with traditional filtering the plants will help regulate
the nitrates/nitrites in the aquarium. The levels are likely to run
higher then 'normal' but won't spike really high when the filtering is
'used up'. You may be lucky and be able to double or triple the time
between cleanings and water changes in the tank - the tank and fish will
tell you if you watch closely. One thing to think about here is if you
harvest all of whatever your growing in the hydroponics, and re-plant
new, the new plants won't be able to absorb as much nutrient as the
previous, mature plants - so keep water changes in mind when you
replant.
Using ancillary hydroponics fertilizers on a
aquaponics system this small may be both required and difficult to grow
healthy plants. The fish's fertilizer production may not be enough for
the plants at certain stages or at full growth. The instructions on the
bottles of fertilizer simply won't cover the small amounts you may need
on these very small tanks, maybe needing half a drop or less of
fertilizer for your tank! You may need to mix your own diluted version
of the fertilizer and use that instead. A bit of math may be involved.
Medium
Aquariums
For me, this is in the range of 10 to 55 gallons.
These tanks are big enough to have 'real' filter systems. They can go
weeks to months without need of cleaning. Tanks of this size are usually
set up on stands, have light hoods, and use over-the-back box filters
or external canister filters. They are still small enough that they can
be moved and set up by a single person.
There are more
options to adding a hydroponics system to a tank of this size. They are
often times big enough to use more then one hydroponic system type on
them at the same time even! If you have a 10 gallon tank, and use a NFT
hydroponics system that holds 1 gallon of water, you lower the water
level on the tank by about an inch which looks fine. On a 55 gallon
tank, you can use an ebb and flow system that has 5 gallons of water
capacity and again only affect the water level on the aquarium by an
inch or two.
There is a beauty to having 'too many' fish in a
tank. By carefully planning and maintaining the hydroponics half of the
aquaponics system, you can increase the total water volume of the system
possibly by as much as 50% of the base aquarium. Holding water in any
trays, trouphs, piping, etc. in such a way that when the power goes out,
you don't over-fill your aquarium would be key to safely overstocking
your tank.
Aquariums of this size give you a good amount
of flexibility in how you set the aquaponics system up. You could
simply place a shallow plastic tub right on top of the aquarium and let
it drain back into the tank for an ebb and flow system. By using a
over-the-back filter designed for deeper tanks, you can hang it right on
the side of the tub with the pickup tube able to reach the water in the
fish tank. You can use an external canister filter in the place of a
regular water pump that is found in hydroponics systems. It pumps and
does the mechanical filtration for you at the same time.
Large
Aquariums
Anything bigger than 55 gallons is a large aquarium. This
is where my love is. I love huge fish tanks. I currently have a 75
gallon tank running, and a 110 gallon tank in storage waiting for my
next move so I have a sturdy enough floor to set it up.
The
biggest problem with tanks this size is there size. They can get so
heavy that many floors can't safely support their weight. If one of
these ever does leak, your in for a big mess!
One of the
biggest boons of a tank of this size is that many of them use a sump
style filter. A sump is basically a small (well, medium sized by my
definition above) tank in the stand of the big tank. Water is pumped
from the sump into the big tank, where it's designed to overflow back
into the sump. When done right, the big tank won't overfill the sump if
the pumps quit working due to power outages. Where these filters are
awesome for aquaponics in an aquarium, is that the tank always looks
full due to any water level fluctuations occurring in the sump. This
means that ebb and flow hydroponics systems won't change the level of
the aquarium, so it always looks it's best!
Really really
big tanks are built with automatic water rotation, auto water level top
off, and other such luxuries. These can be leveraged when re-purposed
into an aquaponics system because they automatically compensate for the
increased evaporation that occurs with the large numbers of plants
involved in systems this big. They can also be used with the types of
fish that are traditionally used in aquaponics - fish big enough to eat!
