To be successful at the
hobby of water gardening,
there are some critical
steps that a water garden owner
must routinely accomplish. If
these steps are not taken, the risk
of losing fish or having an unattractive
water feature increases
dramatically. Worse, the water
feature may deteriorate — and
the work required to maintain it
increase — to the point that the
hobbyist will give up on water
gardening altogether.
These steps or techniques are
fairly simple to understand, but
unless they are discussed, they can
easily be overlooked. In most cases
this discussion should take place
before the pond is built. Proper
pond design, as you will see, can
reduce the effort to accomplish
some of these steps.
[img:1]
To me, it seems easy to decide
which steps are most critical.
However, there are so many aspects
to the hobby that some techniques
may be considered critical by some
and yet not be included here. For
the purposes of this discussion,
know that when I refer to a step
as critical, it means that if it is not
taken, the whole pond’s aesthetic
could degrade into very poor
condition and the fish and the
pond ecosystem could die.
This article discusses what I
consider to be the most critical
steps. My lifetime of experience
has been in the Midwest, but
these techniques are applicable to
all water gardens.
## Step One: Maintain Sufficient Dissolved Oxygen ##
Dissolved oxygen (DO) is
critical to the life we observe
in our water gardens. Fish
have to have it, plants have
to have it (they also generate
oxygen, or O2), and
invertebrates and certain
kinds of bacteria also depend
on O2 to live. Without this
essential element, the ecosystem
will no longer be in
balance and components will
start to die.
Most warm-water fish,
like koi and goldfish, must
have at least five milligrams
per liter of dissolved O2 to
survive. Other forms of life,
such as some invertebrates
and species of bacteria, will
die at six mg/l. Of course,
there are critters that can live
in lower levels of DO, only
needing a few mg/l.
To give you a sense of
the dissolved oxygen range,
maximum DO levels of
70-degree fresh water are
about eight to nine milligrams
per liter. Colder water
is able to hold higher levels of
dissolved DO — as high as
10 to 11 mg/l.
The important aspect of
this discussion is that good
circulation throughout the
entire water garden is essential
to create the eight mg/l that
is necessary for healthy fish
and the entire pond ecosystem.
It is a rare sight to see
too much circulation, but it
can happen. If fish are fighting
a current in most areas
of a water garden, then there is too much circulation and the fish
will become exhausted. As a “rule of
thumb,” it is essential to circulate the
water in a water garden at a rate of at
least one pond volume per hour — but
no more than two pond volumes per
hour — in the smallest ponds, on up
to a 5,000-gallon water garden. This
high circulation rate will maintain the
eight mg/l proportion. It is difficult for
most water gardeners to measure DO,
so it’s safest to simply keep circulation
rates high.
To maintain a circulation rate of
one pond volume per hour in a 1,000-
gallon pond, you would obviously need
to circulate the water at the rate of
1,000 gallons per hour (or GPH). You
can do this with a water pump and/or
an aerator. Once you reach a turnover
rate of 5,000 GPH, then this is enough
circulation for most water gardens
as large as 8,000 gallons. For 5,000-
to 10,000-gallon water gardens, a
circulation of 5,000 to 7,500 GPH is
good. Of course, you can go higher. The
downside of providing even higher levels
of circulation is that it costs money to
create these conditions, and in most cases
it is not necessary for the fish and the
ecosystem. Deciding on circulation rates
for different styles and for larger water
gardens is dependent on the aesthetics
desired and type of filters planned.
## Dead Zones ##
Some pond designs can have the
potential for dead zones, or areas in
the pond that have lower O2. They are
typically created simply by poor design
that blocks the circulation of water to a particular area.
Islands and narrow inlets are two examples
of areas where the water cannot circulate
as well. On a hot summer day or during
a very cold winter where there is a thick
layer of ice, the O2 in these dead zones can
fall below the five milligrams per liter level.
The fish can become stressed, and disease
and even death can occur. In winter, fish
death occurs quickly. Not only fish, but the
whole ecosystem will be affected by these
dead zones — even the lower forms of life,
bacteria and invertebrates, can all die as well.
A sure sign of lower O2 in ponds during
the summer is a proliferation of planktonic
algae (green water). If the pond design is
such that there is the potential for dead
zones, then higher-than-normal circulation
rates will ensure that even these areas will
have sufficient oxygen.
## Step Two: Managing Organic Load ##
Managing organic load is another critical
step for successful water gardening.
There are several aspects to this component.
First, debris (such as leaves) that
was once alive but is now dead needs
to be kept out of the water. Large accumulations
of decaying matter rob the
ecosystem of oxygen, creating anaerobic
conditions and giving off hydrogen
sulfide gases. These gases are toxic to both
the fish and the ecosystem. It smells like
rotten eggs and you will know it when
you smell it.
Managing organic load also means
keeping the fish population in balance
with the size of the water garden. More
fish means more food being introduced
to the pond, which results in more poop.
Each water garden is unique as to
the number of fish it can support. The
amount of circulation, the size and
type of fish, the types of filtration, the
number and kinds of plants and the
temperature of the water all make a
difference in what the water garden can
handle for fish load. It is always better
to err on the low side of population
rather than the high side. So the question
will still be asked — how many fish
is too many? I am very uncomfortable
making any kind of recommendations
in this area without seeing the pond and
assessing its entire system. Adding better
filters and more circulation will partially
compensate for higher fish populations
if that is your goal.
## Step Three: Fish Quarantine ##
The next critical step is one
that is constantly overlooked
but is absolutely necessary:
quarantining any new fish being
added to an existing population.
Adding fish without quarantining
them first is how a lot of parasites
and most fish diseases are
introduced into a water garden.
The horror stories that can be
told — where entire valuable fish
populations have been lost due to
an innocent addition of an apparently
healthy fish or two — are
not in short supply. Creating a
quarantine tank, separate from the
water garden, is essential to keep
new fish isolated for a minimum
of six weeks. Two or three months
are better. The water quality of
these quarantined tanks must be
maintained to the highest level,
including good circulation and
filtration.
## Step Four: Managing Sediment Load ##
The most difficult critical step
is managing sediment load. The
amount of dirt and debris that
is blown, and even washed, into
the pond on a yearly basis is huge.
Some sediment may simply be
organics that have not yet decomposed
but appear to be dirt.
Adding bacteria to decompose
these organics is a good practice
to do on a regular basis.
Sediment that is composed of
minerals, silt and sand (dirt) will
build up in the water garden. This
type of sediment does not decompose,
and some of it will accumulate
on the bottom. Fish will
root around in it and keep some
of it in suspension. Most will
accumulate in filters and plug
things up, creating maintenance
headaches. If these filters are not
maintained by back-flushing or
cleaning, then the filter effectiveness
becomes compromised.
Proper pond design can mitigate sediment
loading much easier than most
realize. Using bottom drains and flushing
valves in filters make maintenance easier.
Almost every water gardener that I know
has to be constantly vigilant in dealing with
sediment. If you are fortunate enough to have
good flushing systems (bottom drains and
sediment basins) and/or good mechanical
sediment filters, then the job is almost
effortless. If the pond does not have the best designs in dealing with sediment, then
maybe a pond vacuum will need to be used
or a periodic whole-pond cleanout will need
to be done. These jobs can be huge but are
essential steps in managing a healthy pond.
I like to think that water gardening
maintenance is no more work than most
other landscape additions. Any developed
landscape has areas that have to be
maintained — mowing, weeding, watering,
etc. Whether you view this as too much work
or not depends on your goals for that landscape.
Some people would argue that water
gardening requires more work, but they all
have critical steps that have to be done regularly.
The critical steps in water gardening —
creating good circulation, managing organic
load, quarantining new fish and managing
sediment — have to be done without fail.
With proper pond design and with the knowledge
of the critical steps for maintenance,
the hobby of water gardening can become
enjoyable rather than a chore.
