Pond Water Quality

When we think of water quality, we usually think of two things:   the water's ability to support aquatic life and clarity.  Clarity is usually not a problem for aquatic life but limits our ability to see and enjoy our fish.  The pond owner should be concerned with both of these aspects.

While it is true that you can keep fish in an ornamental pond with no filtration, it severely limits the number of fish you can keep.  In the wild, fish have large amounts of water so the toxins (ammonia) from their waste do not build up to dangerous levels.  Most hobbyists will want to keep more fish in their ponds than what the pond will naturally support.  Fish 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 which may flow into the pond.

In order to provide good water quality, some form of waste removal system must be provided.  These methods used in the average ornamental ponds are mechanical filtration and biological filtration.  Mechanical filters physically remove solids from the pond by trapping debris usually by a large filter pad.  Mechanical filters are effective but generally require frequent cleaning to remove the accumulated matter.  Biological filtration is the most effective method of removing toxins (ammonia) and breaking it down into nitrites and then into nitrates which provide food to your aquatic plants (referred to as the Nitrogen Cycle).  This is accomplished by using naturally occurring bacteria and giving it a place to live in a biological filter where it is exposed to large quantities of food and oxygen.  This is done most effectively by having a source that provides a lot of surface area for the beneficial bacteria to grow on including rocks, filter pads, Aquamats or bioballs.  You can use our beneficial bacteria products such as our Microbe Lift for small ponds (less than 50' x 50') or our Pond Bio-Solutions for large ponds (over 50' x 50') found here.  Aerators  will also help to increase the efficiency of the biological filter besides add necessary oxygen to the living fish and organisms within the pond.

A biological filter must run continuously during the season and not be shut down for more than a few hours or the bacteria will die.  It should not be cleaned using dechlorinated water (not tap water) as the chlorine and chloramine from the tap water will kill the bacteria.  Care should be given as to not rinse the filter too much and eliminate the brown stain on the filter media.  This brown stain is the bacteria living in the filter pad and should not be removed.

When the biological filter breaks down ammonia into nitrites and then into nitrates, these nitrates are food to the plants in your pond, and to algae if you don't have any plants.  If you keep fish and have no plants, you will also need to do partial water changes to remove the nitrates and other organic compounds from the water.  If you keep sufficient numbers of plants, large water changes are usually unnecessary although small water changes of approximately 10% can be beneficial.  When putting new water into your pond, run the water through some Super Activated Filter Carbon so that it may help dechlorinate the tap water used and not kill your biological filtration during the process.

If you just started a new pond or recently drained and refilled your existing pond, it will take a good month or longer for your pond to find it's balance and for a bacteria colony to start.  In the meantime, your pond can look a bit discouraging - green water and  minimal visibility of your fish.  You'll be tempted to drain it and refill it, but be patient and your pond will find it's own balance.  A newly filled pond with cold tap water and a hot sun beating down on it is a great recipe for an abundance of algae blooms.  Put some barley bales (for small ponds less than 50'x 50') in your pond and this will help combat string algae and plankton (green water algae)  and will work throughout the season providing you with an organic algaecide.  Some algae in a pond is expected, but to create and keep a good balance in your pond, here are a few suggestions:

Here is a diagram to help show the Nitrogen Cycle within a pond:

Þ ammonia breaks down into Þ nitrites, these break down into Þ nitrates which feed your plants and fish Þplants grow and  fish grow but fish excrete ammonia and wastes into pond Þ mechanical filters helps make the water clearer by filtering debris  Þ biological filters breaks down the ammonia into nitrites and nitratesÞoxygen is needed to support health of every living thing in the pond.

Here's a diagram of some helpful steps in establishing a new pond:

new pond water Þadd oxygenating pumps (waterfalls, fountains, etc.)Þadd mechanical and biological filters Þ   wait 3 days    Þ after 3-5 days add aquatic plants (50-70% of surface are should be shade if your pond is in full sun Þ add barley straw and live bacteria Þ after 10 days add no more than 1" of fish per square foot of surface area of your pond Þ algae will most likely occur:  be patient, don't empty your pond, let the pond find it's balance Þ1 month later, you can add more fish but stay within the guidelines on how many fish you can have Þ rinse mechanical filter as needed with a bucket of pond water, don't remove the brown stain which is the live bacteria growing.

To measure the quantity of ammonia and other water chemicals, see our Master Pond Test Kit.