Clear Up the Water by Starting from Scratch

Published on June 30, 2015

What’s in your water? Is it safe? Do you know?

In most instances, a pond owner will fill up his pond with water that is readily accessible and cost-effective. The two typical types of water available are either municipal water (pretreated by the city) or well water (which is drawn from the ground and has had no pretreatment). This, unfortunately, brings unwanted chemicals and additives into the tank and varies significantly depending on the source.


Pond Water TestingThe contaminants found in municipal water typically include things such as chlorine, chloramines and, in some instances, phosphates, metals and an artificially raised pH.

In most instances, well water, on the other hand, is going to carry a much higher hardness than a typical city water, along with metals and dissolved gases such as carbon dioxide.

Another thing to keep in mind is that, regardless of whether a water source is from the city or a well, the water quality may not remain the same every time you use it. These situations show us that the source water will most likely need testing and must be remedied before it can be deemed a safe environment for fish to thrive.


pH is the unit of measure used to determine just how acidic or alkaline a body of water is. Most freshwater fish thrive when the pH level is between 6.6 and 7.8. Bear in mind that rapid changes in pH can cause stress in fish and it is recommended to not alter pH more than 0.3pH every 24 hours. As most source waters should fall well within this range, no initial editing of the water’s pH should be needed. However, it has been known that driftwood and rock will lower pH slightly, and aeration will raise pH. Keeping this in mind when adding aerators or water features can save some headaches in the future.


Aqua UV
 Chlorine is added to municipal drinking water as a way to ensure bacteria and other organics are eliminated before reaching the consumer. Although this is good for drinking water, any level of chlorine can be harmful to fish and should be removed by using a chlorine remover such as Sodium thiosulfate. Chlorine can also be in the water in its combined form, which is also known as chloramines. Chloramines are created by municipalities to increase the shelf life of chlorine and are made by mixing chlorine with ammonia. Chlorine or chloramines will not be found in well water. However, both of these forms of chlorine are harmful and should be kept at a level of 0.0ppm at all times.
Typical Water Makeup
Below are a few items that typically need to be tested, along with their ideal ranges:

  • pH: 6.6 – 7.8
  • Ammonia: 0.0 – 2.5ppm
  • Nitrate: 0.0 – 40ppm
  • Total Alkalinity: 120 – 300ppm
  • Hardness: 100 – 250ppm



Ammonia is produced by decomposing fish waste, decaying plants and unconsumed food. Bacteria is used to convert ammonia to nitrites and eventually nitrates by binding ammonia with water. Both ammonia and nitrates are harmful to fish. However, ammonia at lower levels have the ability to poison a freshwater tank. It is recommended to test regularly for ammonia and dilute when ammonia reaches a maximum of 0.25ppm. But, the ideal ammonia level is 0.0ppm. Another thing to keep in mind is that ammonia is more toxic the higher the pH of your water is. This is caused by the higher pH keeping the ammonia as pure ammonia, whereas the lower the pH, the more ammonia is converted to ammonium ions, which are less harmful to freshwater fish.


Nitrates used to be considered harmless to fish. However, recent studies suggest that high concentrations of nitrates can be harmful. In addition to causing unhealthy fish, an abundance of nitrates can also feed algae blooms, making the water cloudy and leading to a buildup of ammonia.

Total Alkalinity

Also referred to as Carbonate Hardness or KH, the total alkalinity of your water determines how well the pH is going to stay at its current reading. A lower total alkalinity will allow the pH to fluctuate easily, which can be stressful to fish and also stunt the growth of live plants in the tank. In the opposite instance, a higher total alkalinity can be difficult to adjust if the pH is too high. Typically the carbonate hardness is measured in dH, or degrees of hardness. To get dH from ppm, divide your ppm result by 17.8. To get a ppm reading from a dH result, simply multiply your dH result by 17.8.


Hardness is also known as General Hardness, which is the amount of dissolved calcium and magnesium in water, typically measured in dH. The terms “soft” and “hard” water are used to generally describe the level of hardness. The lower the hardness, the softer the water. And the higher the hardness levels, the harder the water is. As most hardness is supplied from calcium carbonate levels in water, editing the hardness can lead to changes in the total alkalinity. It is typically recommended to only edit the hardness if absolutely necessary.
Pond Water Contaminants
The parameters above are essential for aquarium testing. However, other parameters that might need observing include copper, phosphates, nitrites and salinity. Each type of fish will have its preferred environment, which must be understood before determining the correct levels in a pond. For example, some fish prefer a softer water, while others thrive best in harder water situations. Doing research before testing is very important to not only ensure the correct environment but to select the appropriate test kit. As the world moves toward a digital era, so too do testing devices. The benefits that a digital kit can offer include higher degrees of accuracy, easier test procedures, no color blocks to analyze, data management and storage.

In conclusion, it is extremely important to not only know what is in your water, but how each parameter can affect the livelihood of an aquatic ecosystem. Be mindful of where the source water is coming from, what the initial water balance is and where each parameter needs to be to ensure a healthy and productive environment needed to obtain the desired end result.

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