Brita Water Hardness Test kit

Water from most sources has some level of mineral salts dissolved in it (purified water such as distilled or RO filtered [reverse osmosis] are clear exceptions). Among these dissolved salts are certain specific minerals that strongly affect the pH of your water. The concentration of these minerals in your water is often described by the term “hardness” – the higher the concentration of these minerals, the “harder” your water is. There are two types of hardness in water – “carbonate hardness” (KH), which is sometimes also referred to as the water’s “buffering capacity” or “alkalinity” (not to be confused with an “alkaline” solution which would have a pH of greater than 7) and “general hardness” (GH) which refers to the concentration of calcium and magnesium ions in the water.

The general hardness of the water affects pH but it is the buffering capacity (KH) of your water that is the more critical pH factor. This buffering capacity acts like an invisible sponge that soaks up whatever acid or base is in your system – or that you add to your system – until the capacity of the buffer is “used up”. With this sponge-like behavior in mind, imagine trying to adjust your pH. Let’s say you have a pH of 8.0 in your aquaponics system and you would like to bring it down to 7.0. You start adding an acid…and adding…and adding…and little or nothing changes. And then all of a sudden the pH plummets. What has happened? You had a strong buffer (meaning there was a lot of KH) in your system which you eventually “overwhelmed”. Another way of thinking about this is that you “filled up” the sponge.

You can measure your KH level using this test kit. The larger the KH number, the more resistant your system will be to attempts to alter pH. Having a higher KH level can be beneficial in a fully cycled system because, as you will recall, the nitrification process produces nitric acid which will persistently drive pH down in an unbuffered environment. A rule of thumb is that a KH of less than 4 dKH (“dissolved carbonate hardness”) means that you don’t have much buffering capacity and you may see rapid, frequent swings in pH.

The Brita Water Hardness Test Kit is the all-in-one kit you’ll need to determine the hardness of your water.
The kit also includes the Brita drop test kit which helps determine Temporary Hardness (also known as KH or alkalinity) which helps set up the correct bypass.
Before usage, check that the test kit is still in date – see side of box (an out of date kit will give an incorrect reading). The result will determine the bypass setting required on the filter head at installation.