Koi Pond pH Buffers: How do They Work?
More Top Pond Keeping Tips: Click image right for UK pond products. To determine an approximate average depth of your gold fish or koi pond whose depth is not constant take a stick and mark it in intervals of say 3 inches with an indelible ink pen. At 10 different places in the pond insert the stick and record the depths (10 numbers). Add the numbers together and divide by 10. Use this answer as the average depth of the pond. Of course the units depend upon the ruler used. This method of estimating depth is a precursor to calculating pond volume since average depth multiplied by surface area = volume of pond water.
What we often don’t realise when we marvel at the beauty of a thriving koi fishpond is that there are thousands of micro-bioreactions taking place that, although invisible to the naked eye, are responsible for the health and well-being of our treasured koi or goldfish.
When certain treatments are added to a garden fishpond, they also operate on an unseen level, ensuring that our pond’s water quality remains in a stable condition. Two common additives are clays and buffers which instantly interact with pond water on a molecular level. As a koi keeper, it is helpful for you to know exactly what happens when you add any of these two additives.
What is a Water pH Buffer?
A helpful analogy when attempting to understand what a buffer does is to think of it as a sponge that works by soaking up free hydrogen ions, thereby stabilising pond water pH. Therefore, a buffer is any material or compound that behaves in this way, with the most common buffer being calcium carbonate or matter which contains calcium carbonate like calcified seaweed, limestone chippings or cockleshell.
How Does a Buffer Work?
The benefits of good water quality cannot be overemphasised. A pond’s pH is especially important in this regard.
Ideally, your pond’s pH should remain between pH7 and pH9, as extreme fluctuations in pH can have negative side-effects on the health of your fish. Normal fluctuations during a 24 hour period say between 7 and 8 are quite normal (see pH detail at end of article)
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What is pH? It is a measure of the quantity of free hydrogen ions (H+) in your pond water. The more H+, the more acidic the water will be and the lower the pH. This is where buffers come in – to stabilise the pH.
Compared to a natural pond which experiences an inflow of freshwater and the inherent presence of certain minerals, a constructed koi pond has a higher stocking rate and significantly less contact with natural minerals and diluting water. It is therefore inevitable that a manmade koi fishpond’s pH will begin to drop.
Biofiltration processes are taking place all the time as your koi excrete ammonia which has to be processed into nitrite by bacteria. This process causes H+ to be released, thus making the water more acidic. Another factor which influences the acidity of the water is respiration which releases carbon dioxide that combines with water to form carbonic acid. It’s not only your koi that respire, but also the heterotrophic bacteria and pond plant life. It goes without saying then that the acidity of your pond needs to be addressed.
Buffers work by attaching to free hydrogen ions (H+). When hydrogen is unattached, it can cause the pH of your pond water to drop, but when attached to another compound then it will no longer affect the pH. Calcium carbonate, a common buffer, can be placed in you filter to react and bond with free hydrogen ions to form calcium bicarbonate, a soluble compound that cannot influence pH. What this essentially means is that you can protect your koi pond against fluctuations in pH by keeping undissolved calcium carbonate in your filter.
