How to Keep Water Quality High
in Garden Ponds & Water Gardens
Print our Fish
Care Chart for keeping
detailed data on your pond water.
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When we think of water quality in our water gardens and garden ponds
we usually think of two things: the water's
ability to support aquatic life and its clarity. Lack of clarity is usually
not a problem for aquatic life, but limits our ability to see and enjoy
our koi and goldfish. The pond owner should be concerned with both of
While it is true that you can keep goldfish and koi in garden ponds
with no filtration, it severely limits the number of fish you can keep.
In the wild, fish have large amounts of water so that toxins from their
waste do not build up to dangerous levels. Most hobbyists will want to
keep more fish than their garden ponds will naturally support. Goldfish
and koi excrete waste into the water in the form of ammonia, primarily
through their gills. Also adding to the problem are organic compounds
from fish feces, plant matter, and soil that may flow into the pond.
In order to provide good water quality some form of waste removal must
be provided. Two methods used in average water gardens and garden ponds
are mechanical filtration, and biological filtration. Mechanical filters
physically remove solids from the water by trapping the debris in some
form of mat, brush, or sponge. Mechanical filters are effective but generally
require frequent cleaning to remove the accumulated matter. Most biological
filters are also mechanical filters depending on how they are used. For
example, our Signal
In-pond Filter model 800 is a mechanical and biological filter when
used in small ponds where this is the only filter. But it is primarily
considered a mechanical filter when used in combination with another biological
filter in larger garden ponds or water gardens. The mechanical filtration
in most ponds is in the form of a pond
Biological filtration is the most effective method of removing toxins
from water gardens and garden ponds by breaking down ammonia into nitrite
and then into nitrate. This is accomplished using naturally occurring
bacteria called nitrosomonas and nitrobacter. Ammonia is broken down in
natural bodies of water, but we must greatly improve on mother nature
because of our limited space in and around the garden pond. We must provide
a very efficient place for the bacteria to live and thrive. In a biological
filter this place is a material on which the bacteria is exposed to large
quantities of food and oxygen. One of the best materials for accomplishing
this is a fiber matting media which offers a large surface area for the
bacteria to colonize and also a large void area to allow large amounts
of water to flow through carrying food for the bacteria. The Water Garden's
Filter Media accomplishes this better than most other mat type materials.
Another excellent filter material is SpringFlo
Bio Ribbon. This material is more open thus requiring less frequent
Filter materials that are too dense will clog and not allow the water
to flow through. We can also increase the efficiency by adding concentrated
solutions of bacteria and enzymes such as Microbe
Lift PL and Microbe
Lift NiteOut. Providing an abundant supply of oxygen to the bacteria
by the use of air stones or aeration towers in the filter will also increase
the efficiency. There are also other organisms
such as Blood Worms which colonize in a biological filter and help break
down organic compounds.
Biological filters in water gardens and garden ponds must run continuously
during the season. If they are shut down for more than a few hours the
beneficial bacteria will begin to die. A biological filter should be cleaned
using dechlorinated water if possible to avoid removing or killing the
beneficial bacteria. Also the filter should not be over cleaned, rinse
the media only enough to allow good water flow though the filter. The
brown stain on the filter media is the living bacteria.
The nitrates that result after the breakdown of ammonia and nitrites
are food for the plants or food for the algae if plants are not available.
If you keep goldfish or koi and no plants you will also need to do partial
water changes to remove the nitrates and other organic compounds from
the pond water. If you keep sufficient numbers of aquatic plants, large
water changes are usually unnecessary although small water changes of
approximately 10 to 20% every 3 to 5 weeks can be beneficial.
At certain times of the year or if the balance of fish, plants and biological
filter is off you may still experience green water in your garden ponds
or water gardens due to a build up of single cell algae.
The best method of guaranteeing clear water against this problem is
through the use of an ultraviolet
sterilizer. This device uses a small germicidal UV lamp that is placed
in a pipe to allow water to pass all around and will give a near 99% reduction
in algae when properly sized to the pond. However an ultraviolet sterilizer
must not be used without adequate biological filtration as the dead algae
still needs to be broken down by the filter. UV will not help with string
algae, for this we recommend AlgaeFix,
Cleaner. Also strive to achieve a balanced system using the methods below
to keep string algae to a minimum.
There are many types of algae. There are different colors and textures.
The green velvet type that grows on the sides of the pond is a very beneficial
type of algae providing oxygen and food for goldfish and koi. This algae
also gives a more natural appearance to garden ponds and water gardens.
We get some calls asking how to get rid of this type of algae. Our answer
is, if you can't tolerate this type of algae then you will need to get
rid of your goldfish and koi and use a product called Fountec.
Fountec is a product that will remove this type of algae and it is safe
for plants and all animals except fish.
If you only occasionally have problems with algae or other suspended
particles which interfere with water clarity in your garden ponds or water
gardens then you might consider a flocculant such as Accu-Clear.
This type product works by causing particles in suspension to clump together
and then fall to the bottom of the pond where it must then be removed
by siphoning or vacuuming from the bottom, or a mechanical filter can
be used to remove this debris.
Another useful product to aid in improving water quality in garden ponds
and water gardens is a packaged bacteria and enzymes combination that
will break down sludge and other organic compounds. Microbe
Lift Sludge Away will help reduce organic buildup and sludge..
For your fish to be healthy and also to help with the control of algae,
the pH of the garden pond water needs to be monitored using a pH
test kit. The pH should be between 6.8 and 8.0 with the ideal being
7.0 to 7.8. Unless the pH is below 6.6 or above 8.4 then it is usually
best not to try and adjust it.
If you need to adjust the pH of your pond water we have pH
Up Liquid to raise the pH and pH
to lower the pH.
How to Balance Your
Garden Ponds & Water Gardens
One major concern for water garden and garden pond enthusiasts is achieving
and maintaining clear water. When water gardens and garden ponds are first
constructed there is usually a rush to fill them up with fish and aquatic
plants, but it is important to consider the natural process of these ecosystems.
In nature a pond has a period of time for all the components to adjust
and interact as the pond evolves. Although suspended algae in water gardens
and garden ponds is to be expected most people want to keep it to a minimum.
Constructed water gardens and garden ponds require help in order to avoid
problems with excess algae. One method to control algae is to stock and
arrange the pond with this method:
- Keep rain run-off out of the pond. It carries with it soil, fertilizers,
and chemicals which will prevent the pond from balancing.
- If in full sun, shade 50 - 70% of the pond surface. Do this with
the leaves of water lilies and floating plants. If your pond is in less
than full sun, less surface coverage is acceptable.
- Use one bunch of Anacharis
per one sq. ft. of surface area for ponds under 50 sq. ft. and one bunch
per two to three sq. ft. for ponds over 51 to 200 sq. ft. For ponds
over 200 sq. ft. use one bunch for every three to four sq. ft.
- Use no more than one inch of fish per sq. ft. of surface area initially.
After the pond has fully established or with well filtered water, more
fish may be added. Feed only what the fish can eat in 5 minutes. Uneaten
food feeds algae.
- Add biological
filtration and an ultraviolet
- Remove any dead organic matter from the pond.