We get a lot of questions about water quality, measuring water values and the meaning of different values. Therefore, this time we are writing a blog about water quality and water values.
Keeping a pond in the garden is a fun activity. The sight of fish swimming around beautifully calmly is golden for many pond lovers. However, keeping the water quality up to standard is sometimes a tricky business. Creating a natural balance in the pond is difficult because ponds are often not that large and yet there are many fish swimming in them. In addition, of course, everyone wants pond water to be as crystal clear as possible. 
Proper water quality is important!
Therefore, a number of measures must be taken to ensure proper water quality. If you do not do this, you are likely to have algae growth or sick fish. These include applying pond substrate and aquatic plants and installing a filter and other equipment. Yet several processes take place in a pond, which can easily change water values. Fish that need to get rid of their droppings, a big downpour or just a few days in a row of warm weather and sunshine. It is therefore important to measure the water values every week. This doesn’t take much time and you always know for sure what the water quality is like. Do you suffer from green pond water? Then read our blog“How do I get my pond clear again“. 
There are many different water values, the most important are the: pH value, GH value and the KH value. We will cover these values below. These and other values are easy to measure with the liquid test or test strips from Velda and keep track in the special Velda app.
Measure pH value
The pH value indicates how acidic water is. Acidic water has a pH below 7. Alkaline water has a pH above 7. Understanding the pH value of pond water is very important because it tells us something about the CO2 content in the water. If we want to measure the pH value (or CO2 content), we also need to measure the KH value, the carbonate hardness. If both values are known, we can fairly accurately read the CO2 content per liter of water. Good plant growth requires at least 5 mg of CO2 per liter of pond water.
If early in the morning the pH is relatively low (pH 7 – 8) and measured relatively high in the evening (pH 8 – 9) then the pond environment is functioning, the plants will grow well and the water will be clear.
An excessive pH level (pH 9 to pH 10) need not be a problem, but is always the result of a poorly functioning pond environment. For example, it may be that the activity of microorganisms is nil. It may also be that biogenic decalcification is taking place in the environment due to excessive algae growth. To get the pH value back to the right level, Velda has developed special pH min. Click here for more information on pH value
Measuring GH value
The combined hardness of water is determined by calcium and magnesium. This is called the GH value of the water and is expressed in German hardness degrees (°dH). A proper GH value for pond water is between 8° and 12° dH. This is important for several reasons. Most types of pond plants grow optimally within these values, and furthermore, in this medium-hard water the development and activity of microorganisms is optimal. Oxygenation is also best guaranteed at these values.
Due to weather influences (rain, hail, snow) and biological processes, pond water is constantly softening. Therefore, also check this value weekly with Velda’s water tests. Click here for more information on the GH value. If the GH value in the pond is too low, it can be increased over a long period of time with special agents such as GH plus.
KH value measurement
The carbonate hardness or KH value, is an important pillar in the pond environment. The KH value is called temporary hardness. It is also referred to as the acid-binding capacity.
Carbonate is created by binding free carbonic acid (CO2) to calcium and or magnesium. It thus forms a carbonic acid (CO2) buffer for aquatic plants and algae. When the pond environment (microorganisms) releases enough CO2 to cover the needs for plant growth, the KH value will remain stable. However, when the plants’ need for CO2 exceeds the supply, the CO2 source from the carbonate will be tapped and the KH value will drop. A good KH value lies between 6° and 8°dH. A simple test can also be used to determine this value.
In new ponds, but also in stagnant ponds, it may be necessary to increase the carbonate hardness. For this purpose, special agents are available that increase the KH value long-term, such as KH plus. Click here for more information on the KH value in the pond.
We hope it has become a little clearer what values are happening in the pond. If you have questions about this blog or any other question, please ask via our Facebook page and we will be happy to help you. In addition, several questions can be found on our frequently asked questions page.
