Water hardness | What exactly is hard water and why pond water testing is not necessary
Water hardness, it is often talked about by pond owners and pond enthusiasts, but what exactly is it and is it necessary to test the hardness of your water or is it unnecessary when you rearrange your pond? In this blog I, Simon as a pond specialist will tell you all about it.
What does water hardness mean?
When talking about water hardness and measuring it, many people will initially wonder what it is. Water hardness can literally be translated to the hardness of the water in the pond. It is often recommended to measure the water in the pond for hardness, 3 water values are then tested: The total hardness (GH value), the carbonate hardness (KH value) and on the oxygen level (pH value).. But what many people don't know is that you don't need to measure the hardness of your water at all if the pond is set up properly.
What is the ideal hardness of water?
The ideal hardness of the water in your pond is determined by the combination of the GH value, KH value and the PH value. Water values and therefore hard water is expressed in DH, which stands for German Hardness degrees. The correct hardness of water is between 8 and 12 DH. So this can be seen as ideal water hardness.
Pond substrate and pond bacteria
What are good water values for the pond?
Pond water values today can be measured in a variety of ways. There are all nice values established for it, making it clear when the quality and hardness of your water is good. But did you know that measuring and keeping your pond water between the desired standards is a difficult or even almost impossible task. This is due to the changing weather conditions we face. This means that 24 hours after measuring, the water in your pond can look completely different again. For this reason it is not realistic to always keep your pond water within these standards. But what is the solution? Well I have the perfect answer, because I have created a step-by-step pond construction plan that describes exactly how you can keep your pond healthy by adding the right amount of substrate, oxygen plants and pond bacteria without having to monitor the hardness of the water.
Simon's top 3 favorites oxygen plants
How do I get my pond clear again?
To get your pond clear, or better yet, to keep it healthy from construction, you can follow some steps that are guaranteed to lead to success, provided you follow the steps correctly, of course. In fact, it is not at all necessary to measure the hardness of your water or to soften the water in your pond. People often talk about lime in the pond but this problem does not arise when the pond is set up correctly, i.e. with substrate, bacteria, oxygen plants and so on.
Frequently asked questions about keeping fish in the pond
Water hardness 1 means that there are 17.8 grams of lime in the water per 1,000 liters of water. The average hardness of water is between 8 and 12 DH.
When the water in your pond is between 0-4 DH it means your water is very soft, a water value between 4-8 means your water is soft, between 8-12 means the hardness of your water is average and a water hardness between 12-18 DH means your water is quite hard. A DH between 8-12 is ideal.

Simon van der Velde
Pond specialist and aquatic plant grower since 1986
Simon's vision is to let nature do its work in your pond. No need to buy all kinds of measuring equipment and water improvers. If the fish are swimming nicely and the plants are growing well, then the water in the pond is of good quality. With a good planting plan and the right approach, you can save a lot of money and maintenance, and ensure a clear, biologically balanced pond that becomes more beautiful every year.