We live close to our company JBL in Speyer. Unlike in Hamburg, where I spent my childhood, it doesn’t seem to rain here very much. Within a week the water level of my pond can drop quite perceptively in summer, and even in spring. Being a little on the lazy side I have been known to top up the pond now and then with tap water. But when I test the water afterwards I get my comeuppance. After a steady increase the general hardness (GH) of the pond water has become significantly higher. With this test result in front of me I’m forced to admit that this is not the way to refill the water. It can even lead to more problems. That’s why I now let my pond water intentionally overflow at one spot and fill in new water for 15 minutes. After 2-3 water changes the values normalise and roughly correspond to my tap water values.
When it does rain it’s a different story. When it’s not sunny here it really buckets it down and the Rhine almost breaks its banks. Heidelberg town centre floods and my pond silently cries for help, as this rainwater dilutes the mineral content of its water to a massive degree. The increasingly softened pond water is no longer pH-stable and it can fluctuate between 6.5 in the morning to 9.5 in the evening. This corresponds to a thousand time raise in the acid components, since the pH value is measured on a logarithmic scale. The only way I can stabilise the water now is by adding minerals. For that I use JBL StabiloPond basis . A partial water change in the pond after extremely strong rainfall also helps but I don’t much like fiddling around outside at the pond when it’s raining. I prefer to add minerals, even if this costs a bit of money.
Water changes have several additional benefits: potentially dangerous substances, such as nitrates and phosphates, are removed from my pond, minerals are added (as already mentioned), and any colour cast in the water, caused by the humin components of plant soil, is reduced. In fact, a partial water change is the ideal maintenance measure for almost every problem in the pond. You definitely have to test the tap water beforehand ( JBL Testlab Koi ). It can sometimes be so full of phosphates or nitrates that it is unusable. A good water conditioner, such as JBL BiotoPond ensures that it binds all heavy metals like lead, zinc and copper in the tap water system. In a nutshell: a partial water change in the pond is really important!