Water Quality Parameters for Your Pond


Your pond’s water quality to your fish is as important as our air quality is to us.  With that said, do you test your pond water?  And if you do regular testing, do you even understand what those tests mean?  This article gives you a look into each of the common testing parameters available in most water testing kits.


The pH of your water is the amount of hydrogen ions that are present in your water.  The pH scale has a range from 0-14, acidic to basic (alkaline), respectively.  The midpoint, 7, is considered neutral.

Your pH controls many of the chemical balances in your water.  One very important chemical balance is that it affects the toxicity of the ammonia in your pond.  In general, the higher your pH and water temperature, the higher the ammonia toxicity will be in your tank (if ammonia is even present).


In your pond, fish will release waste into the water.  In addition, decaying plant matter and uneaten fish food will break down.  All of these activities will create ammonia.  This buildup of ammonia is lethal to fish, especially at escalated pH levels.  If left untreated, ammonia will damage delicate gill membranes, causing respiratory distress or death.  As the ammonia levels increase, beneficial bacteria named Nitrosomonas will begin to consume and convert the ammonia to nitrite (NO2).


As stated in the previous paragraph, Nitrite (NO2) is the result of beneficial bacteria named Nitrosomonas consuming ammonia and converting it to nitrite.  Nitrite is extremely toxic to fish, preventing the fish’s blood from carrying oxygen.  This prevents the normal gas exchange from their gills.  If severe enough, the fish will die from oxygen starvation.  So clearly, this is yet another important parameter at which we should monitor.

If your pond is established and your nitrite level is in check, it’s probably safe to say that you have abundant amounts of the beneficial bacteria named Nitrobacter.   It will consume and convert the nitrites to nitrates (NO3).  This newly converted nitrate will then be consumed by plants and algae as source of nourishment.


Monitoring your phosphate level is important because it is one of the primary nutrients responsible for algae blooms.  Common phosphate sources include decaying plants, waterfowl excrement and treated landscape run-off.

Carbonate Hardness (KH)

Carbonate Hardness, or alkalinity, is the measurement of the water’s ability to neutralize acid, known as the buffering capacity.  Buffering capacity is the water’s ability to keep the pH stable as acids or bases are added.  So if the water has sufficient buffering capacity, it can absorb (like a sponge) and neutralize additions without affecting the pH.  There is, however, a limit on the sponge’s ability.  Once this limit is reached, the pH can change rapidly.

Carbonate Hardness is also an important source of energy for nitrifying bacteria that consume ammonia and nitrite.

General Hardness (GH)

General Hardness, or Total Hardness (TH) is a measurement of the dissolved salts in the water, mostly composed from calcium and magnesium.   The concentration of dissolved salts is important to fish for 2 reasons:  Osmotic regulation (equilibrium of the internal salt concentration) and blood calcium levels are regulated by the amount of General Hardness levels.

New Plant Hardiness Zone Map Reveals Warming Trend



The USDA released their new version of the Plant Hardness Zone Map in January 2012. The new map is generally one 5- degree Fahrenheit half-zone warmer than the previous released map back in 1990. This mostly is a result of using temperature data from a longer and more recent time period. More specifically, it uses data measured at weather stations during a 30-year period from 1976-2005. The 1990 map used data from a 13-year period of 1974-1986.
Another change with the new map is the addition of an interactive “find your zone by ZIP code” function. Click here to see the new USDA Plant Hardiness Zone Map.

Koi/ Goldfish Spawning

I remember in my early years of ponding my first encounter with spawning.  One early summer morning, I noticed something different happening in my pond.  My first visual clue was a pond full of white foam as well as, a strong fishy smell.  My first thought and concern was that there had been predators in the water stirring up the water.  After doing some research, I realized that my koi were spawning.  How exciting!  So, you want to understand more?  Keep reading!

Under normal conditions, distinguishing between male and female fish can be quite difficult.  Females normally have a larger girth to them and during the spawning months, they will have a swollen underside.  This swollenness is a result of hundreds of eggs waiting to be released.

When the fish spawn, you may notice several thinner males chasing the female(s) around the pond.   They will bump against her sides and stomach area in an attempt to release her eggs.  Once her eggs are released, the males will release their milt, fertilizing the eggs as they adhere to underwater plant life or some other shelter.  Without some form of proper shelter for the newly created fry, adult koi will eat their young.   Mother Nature does provide her own way of keeping fish populations in check this way.

I have my own experience with actually transplanting water hyacinth from a larger pond to a smaller pond.  It was later that I realized the water hyacinth roots had koi eggs housed in them.  These fry successfully lived in the smaller pond.   I initially fed them koi food crumbs until they grew big enough to eat “big fish” food.

More important spawning information to consider:

  • Spawning occurs between March- July, or when water temperatures are between 68°F – 72°F.
  • Spawning normally occurs in the early morning hours or late evening.
  • Healthy eggs will be translucent while unfertilized eggs will be white and will start to grow fuzz.
  • Keep water quality in check to assure a healthy environment for spawning to occur.
  • To ensure survival of some of your fry, provide shelter using plants or manufactured spawning ropes and brushes or isolation.


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Maintaining Your Pond During the Winter

If you live in a colder winter climate and have chosen to allow your pond to run throughout the winter, then you are probably already aware that this will require maintenance in bitter temperatures.  Whether or not you decide to allow your pond to run all winter long, below are some items to consider.


Just as your water levels need replenished due to evaporation in the warmer weather, the same is true for colder temperatures as well.   Adding water may become more challenging in the winter with normal water sources shut down.  Some options for adding water include:  making multiple trips with a bucket or running a hose from an internal faucet.  There are many pond owners that perform partial water changes on their ponds during the winter to relieve the pond of harmful buildup of ammonia and nitrites.   While adding water is not convenient in the winter, it is an important part of maintaining your pond during these cold temperatures.

Water Circulation

Be aware, that pump size is a critical factor in determining a waterfall’s ability to operate during the winter.  In most situations, a pump size of 2,000 gph or bigger can be operated during the winter safely.  If you are presented with many sub-zero temperature days, your system may not function normally due to ice build-up.  Carefully monitoring your pond during these extreme temperatures is important.  It may become necessary to shut your system down until the ice has melted and normal water flow can be restored.

If you decide to shut your pond down due to these extreme temperatures, be sure to consider a few maintenance steps.  Always be sure to follow your manufacturer’s recommendation for properly storing your pump.  Also remove and rinse the filtration media and place in a frost-free location for ease of replacement in the spring.


If your pump has been shut down, it is important that some form of aeration be provided to allow for an opening in the ice.  This allows for the escape of harmful gases to be released.

There are several great options when considering alternate forms of aeration.  The Aquascape AquaForce® is a great winterizing pump.  This recirculating bubbler pump is designed to sit in the pond and oxygenate the water.  Simply place the pump in the water, positioning the discharge pipe below the surface of the water.  The bubbling from the pump will maintain a hole in the ice, which will help increase oxygen levels and allow for dangerous gases to escape.

The addition of a floating de-icer in combination with the bubbler pump is recommended for extreme prolonged cold winters to insure there will be a hole open in the ice all winter long.

In Conclusion

Whether you run your pond all winter or shut it down is a decision to have to make based on how much maintenance you want to perform during these extreme temperatures.   The beauty of beautiful ice that is created from the water may be rewarding enough to consider maintaining it all winter long.