You should know if the pH stays at over 8.5 for any amount of time, the Koi fish will become diseased or stressed. Usually, alkaline conditions are more common than acidic in ponds, especially if it`s a new pond.
Some of the symptoms include lethargic fish due to their damaged mucus coating, which is prone to fungal infection and other diseases. Plants have a chalky appearance because of calcium deposits. There`s a prominence of waste chemicals that will hurt pond life and the biological filter has lost it`s effectiveness.
Some of the things that can cause the pH to rise include introducing fish too soon, to a new pond that was not sealed properly; the lime or alkali from the cement will cause the pH to top the scale. Even one shovelful of concrete or mortar can cause very serious problems. Lime that leaches from blocks, stepping stones or other cement products and similar materials over a period of time as well as lime in stone products are subject to erosion and the excessive growth of algae are also contributing factors as well.
To solve this problem, you can allow enough time for the pond to age before adding fish. Try introducing bacteria found in a Koi pond starter kit to speed up the process. Do a partial water change to dilute the alkalis. If it`s due to algae`s excessive growth, remove the growths. If none of those steps help reduce the pH level, you can purchase an acidifying compound or a pond pH buffer.
In a low pH level Koi pond, fish may become stressed, get sick and start dying off. This could be caused by excessive amounts of rain, which causes the pond to lose it`s buffers and this loss can cause drastic fluctuations in the pH. Oxygenating plants like Hyacinths, Elodea, Anacharis and Water Lettuce become wilted and discolored. The filtration also stops working properly.
To solve this problem, do regular partial water changes. Add a buffer of a mesh bag of oyster shell gravel, crushed coral or dolomite in the filter or waterfall. Use pond-buffer salts found in the pond supply store.
For smaller Koi ponds, you should replace 20% of the pond water a couple times a year and keep all rotting debris such as dead fish and plants cleaned from the water. For more info, you can visit: www.askdoughoover.com
Image source en.wikipedia.org used with permission
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