With so much rain about in winter, many will be right to think that it’s great for fish in ponds. It poured in Perth last week, and in Melbourne this week. All this water will dilute dissolved wastes, and top up your ponds without you having to do any work. All good! But is it?
Along with diluting wastes, rain water will also dilute your buffers. In cities where there is considerable air pollution, the rainwater can actually be a little acidic. This will consume your water buffers. The ultimate effect can be, that the pH of your pond water can become rather acidic.
My suggestion is to monitor your pH and your alkalinity. For goldfish and koi ponds, maintain your pH at neutral (7.0), and your alkalinity at 50-100 mg/L.
I have a few concrete pond set ups and sometimes I use 50% of rainwater and 50 tap water when doing 100% water changes. I also add some premium pool salt to it. Is there a chemical I can add to purify this water? I know in some Asian countries they do this add something to purify it.
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Hi Tivan, tap water contains chlorine and chloramine, which are toxic to fish. When doing such large water changes, it’s best practice to use a product to neutralise those chemicals. Water conditioners can be bought from all aquarium shops.
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