Ponds 101

The 5 Elements to Healthy Pond:

1)     Filtration

  • A skimmer keeps the water clean by removing debris as it falls in. That way it doesn't sink to the bottom to decay. The skimmer houses the pump and a filter pad to help the pond looking great.

2)     Rocks and gravel

  • These provide surface area for good bacteria to colonize, which helps keep algae under control.

3)      Recirculation

  • The movement of the water helps keep it oxygenated. This is beneficial for the fish and plants, which, in turn help keep algae in check. It keeps the water from being stagnant.

4)      Fish

  • Fish eat algae as well as add nutrients back into the water. Watching fish has proven to be very relaxing!

5)      Plants

  • They are additional living filtration. A great way to keep a pond in balance is to have lilies, floating hyacinth and other plants.  Just like regular garden plants, there are plants that over winter here in zone five.

Ponds and the Environment

Pond Information - areationInstalling a pond not only brings beauty to your outside living space and gets your family outside, but it also benefits the local wildlife.  Ponds attract birds, dragonflies and frogs!  All of these fabulous creatures eat the insects that bug us!

Ponds also conserve water!  YES!!  We water our lawns about twice a week here in Colorado.  Some people water more than that.  A 10 x 10 area that is watered twice a week uses 124 gallons each week -- 25  times!  That is 3,100 gallons a year.    A 10 x 10 pond holds about 1800 gallons of water.  While it may need additional water once in awhile, that is only 180 gallons or less.   We also don’t have to use the lawn mower on our pond, saving time and pollution.

Fish Care

Establishing a balanced pond ecosystem is the easiest way to ensure healthy fish, which are in turn an important part of that balance.  Caring for them can be easy!

Aspects of fish care:

  • Many people enjoy feeding their fish and some can be trained to eat right from your hand!  Only give them what they can eat in a few minutes and remove any excess food to prevent decay in the water.  Some pond owners feed the fish once or twice a week.  Some people enjoy feeding them daily, but remember that overfeeding can overload the filtration system with excess waste.   The fish will naturally eat algae from the pond so there isn’t a true need to feed them daily.
Safe Water Addition
  • If water needs to be changed or added to the pond - more than 20% of the total volume- make sure to add a detoxifier.  This removes and detoxifies chlorine from the water.  Chlorine can burn the gills of the fish, so make sure not to add large amounts of regular tap water to your system without detoxifier.
  • Oxygen
    • Make sure your pond has a running waterfall and aerators where the water has little flow.  This provides the needed oxygen to fish.
  • Predators
    • Raccoons and heron can be a predators of your lovely pond fish!  Adding a fish cave, a scarecrow (automatic sprinkler head activate by movement), and even a net over the pond can deter predators.  While they are often not a problem, if you find yourself with unwanted guests you'll want to get rid of them fast!

How Many Fish Can I Have?

Over stocking fish creates an imbalance in the pond’s ecosystem and can be detrimental to the health of your fish. A 7 inch koi needs 74.8 gallons of water - or 10 cubic ft.  Generally, goldfish can be kept in closer proximity.

This table is a general guide for fish about 7 inches long. - Remember that the small fish will grow! This also assumes good conditions regarding circulation, aeration, filtration, bacteria colonization and good plant life.

Pond size (assuming a rounded shape at 2 ft deep)# gold fish# Koi
5 x 574
5 x 8127
8 x 102113
10 x 102516
12 x 103019

Want to understand the numbers?  Using the equation to figure out the gallons of your pond you can figure out how many fish you can have. - (L x W x 80%) x average depth x 7.48 = gallons in a pond. We use 80%  here, because ponds are not square, they are about 80% of a square. So if you have a 10 x 8 pond with an average depth of 2 feet it would look like this: 10 x 8 x .80 = 64.  64 x 2 x 7.48= 957.44 gallons.  957.44 divided by 74.8 (assuming a 7 inch koi) = 12.8   I would round up to 13 (no one wants to see 80% of a fish!)


Algae generally occurs in early spring when temperatures begin to rise. This happens because other life in the pond is still a bit dormant.  Without all aspects of the ecosystem contributing to the health of the pond,  algae can go to town! Beneficial bacteria and plants wake up slightly later than the algae does in the Spring. Suspended algae that creates green water that looks like pea soup is referred to as microbial algae.  As temperatures rise and beneficial bacteria colonizes again and plants wake up for the spring they begin to consume some of the excess nutrients in the water, causing algae to subside.  

Algae growth may occur during heat waves in the summer or any time the pond ecosystem is out of balance. If you are experiencing an algae bloom, check to make sure you are not overfeeding the fish.  People love to feed their fish, but more than once a day could be a contributor.  During an algae bloom you should stop feeding the fish!  It will reduce the waste that contributes to algae, and they will eat the existing algae anyway.

String algae, just like its name, has a stringy look and attaches to rock, gravel within the waterfall and pond. Lack of shade may encourage string algae growth.  A heavy fish load or lack of plants can contribute to string algae growth as well. One proven way to keep string algae at bay is to add an IonGen.  When used correctly, it effectively kills algae without the use of other chemicals.

Pond’s are ecosystems within themselves and just like nature, they have to be in balance to be healthy.

Algaecide - Beware - Uses and Cautions

Algaecide may seem appealing and is useful in some situations,  but know that while it may quickly kill off algae, it can quickly kill off your fish too.  Be sure to read the instructions carefully and call a professional if you need help.

Algaecide works by removing the oxygen and suffocating the algae.  It is also hard on plants, beneficial bacteria, and fish.  Algae itself puts oxygen into the water. For that reason we recommend only treating ¼ of the pond at a time.  When treating algae in a waterfall, turn it off and sprinkle dry algaecide onto the area, leaving it sitting without the waterfall on for 30 minutes.

After using Algaecide

The day after using algaecide, make sure you add beneficial bacteria to either replace what has likely been destroyed  or to add it if it has been absent.  When large amounts of algae are present, we know that the balance of the eco-system is off.  Getting it back in balance will help your pond look beautiful again.  Algaecide can destroy good parts of that system so they need to be replaced several times after a treatment.

If your fish are coming to the top of the water and seem to be gasping for air after and algaecide treatment, then too much has been used and you are at risk of losing fish.  Do a partial water change, adding detoxifier for protection of the fish.  You can also put in an aerator to get more oxygen flow going and hopefully keep the fish from dying.

Remember that overuse of algaecide can cause future outbreaks of algae -- worse than the original problem and can damage plants and fish.  If it is necessary to get control of algae, follow directions to the letter and make sure to get the pond into balance after its use. 

Need help finding that balance?  Give us a call! 303-775-0224

Is a Cleanout Right for My Pond?

If your pond has excessive decaying matter or sludge, it’s probably time for a cleanout.  Balanced ponds may need to be cleaned out every couple of years.  Ponds that struggle with balance may need annual cleanouts.   A full cleanout consists of removing the fish (we put them in an on-site portable pond during this process) and draining the pond by pumping out all the water.  The waterfall, the rocks, gravel, and bottom of the pond are pressure-washed, and the remaining gunk is removed. Plants are trimmed as needed, the pond is refilled, and the fish are returned.

One of the most important aspects of a cleanout is actually the caring for the pond in the weeks following the cleanout.  When a cleanout is performed, keep in mind that the ecosystem of the pond is essentially being re-started.  Bacteria needs to be added right after a cleanout and every couple of days right after one to avoid an algae bloom. Beneficial bacteria won’t do you any good if it doesn’t have anywhere to live. Therefore, it is critical that beneficial bacteria have gravel in the bottom of the pond and/or bioballs in the waterfall where they can colonize.

When proper care is taken to re-balance a pond after a cleanout, it will be well worth it!

More on Algae  More Leak Info  More About Pond Plants  More about Fish   More Pond Topics

Or use the SEARCH at the bottom right to look up your specific topic!