The mineral levels and the pH of rainwater can vary greatly. Rainwater is naturally SOFT and fairly acidic, but when it falls to the ground and makes it way into waterways or flows over rocks the water will pick up minerals such as Calcium and Magnesium which begin to make it HARD but this may not always be the case. Carbonate Hardness - KH, is the measure of the amount of Calcium and Magnesium found in your pond. These two elements play an important part in the health of fish and the pond. Calcium and Magnesium help to neutralise acids and stabilise pH levels. When people talk about HARD or SOFT water, this just indicates that your pond is high or low in these minerals. These minerals can play a role in how well treatments, such as algaecides or medicines, work. The KH will also play a part in how well the good bacteria in your pond works as the bacteria needs the minerals to survive. The effects of the SOFT water might not be seen at first but can gradually take effect. With the good bacteria dying off in the pond the ammonia and nitrite levels will begin to spike and without the needed calcium and magnesium in the water there is no buffer to prevent harmful pH swings. This will lead to the ill health of fish and even death. Testing your KH regularly should be done if you use rainwater in your pond. If the water is too soft you can add "Hardness Plus" or "Calcium Carbonate"to increase the hardness.
Chlorine or any other chemicals in the tap water will strip the fish of their protective slime coating, which makes them prone to getting diseases. The chlorine will also kill the 'good bacteria' that you want growing in the pond. Without the 'good bacteria' the ammonia and nitrite levels will rise and can cause the death of your fish. Chlorine Neutraliser water conditioner is available in liquid form to remove chlorine and chloramines from the tap water. The conditioner activates instantly and will need to be added every time you top up the pond. Perth tap water generally contains a suitable level of hardness and the pH is fairly stable.
Bore water isn't something we would generally recommend for fish ponds as levels can vary depending on the situation. Bore water is affected greatly by our own activities such as our use of fertilizers, pesticides, insecticides, chemicals etc. Bore water can also be contaminated naturally by minerals, bacteria and viruses. Bore water can be tested to confirm the quality of the water which can be done by contacting a NATA-accredited laboratory. CLICK HERE for more information on bore water and how it can be tested and treated.