pH of Koi Pond Water. Should I measure pH?

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Page Summary:  I firmly believe the worst thing a pond keeper can do is to measure pH UNLESS (read on) ...  pH is a German initial for potenz Hydrogen or thats what I was told at University. But what is pH really and what does it mean for pond keepers? pH of pond water is a measure of how acidic or alkaline the water in our fish or koi pond is. To make it easier to understand and describe this highly complex property of water and other water based compounds such as acidic and alkaline substances consider the following

pH is in a range of 0-14.

Sulphuric Acid has very low pH. Caustic soda in solution of water has a very high pH

Nearly everybody knows sulphuric acid is dangerous and that it burns the skin. Well sulphuric acid which is an aqueous solution of sulphur trioxide is extremely acidic (very very low pH and corrosive and dangerous therefore). Sulphuric acid is known as a strong acid. On the other hand vinegar which is a solution of the organic acid Acetic acid is a weak acid and as we all know can be taken in small doses with other fish (and chips)

At the other end of the pH spectrum is the strongly alkaline property with a maximum pH value of 14. Solutions of caustic soda would be considered as strong bases or alkalis.

A weak alkali is sodium bicarbonate in solution. This may be taken for upset stomachs or for baking cakes perhaps. Chemical reactions between strong acids and strong alkalis are extremely vigorous and give off large amounts of heat instantaneously.

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Halfway between 0 and 14 is Neutral pH=7

  1. The stronger the acid the lower will be the pH.
  2. The stronger the alkali (or base) the higher will be the pH
  3. Halway between 0 and 14 is pH=7... we tend to think of water as being oh pH = 7 or a neutral pH but this is rarely the case. Water in a pond is either alkaline or acidic. To put this into perspective and to use a real world example consider 2 trout streams in the UK

The one is in the north of Scotland and the water source is essentially rain falling onto stony hills and mountains before running off quickly to form a stream which could quickly turn into a raging torrent. Such a stream would tend to be acidic and would be characterised by low fish populations small in size and low aquatic growth. Fish would be small and stunted in view of poorly fertilised water. Scottish rivers in general are therefore acidic or at best neutral pH=7)

The other stream is in the south of England and is called the River Test. This stream unlike the Scottish one has been formed by rainwater which has first of all sunk into the ground through porous limestone and found its way through these alkaline passages and underground chambers to later find its way out of these chambers to form streams and ultimately rivers. It costs a fortune to fish for River Test trout because of the quality of water and the fact its high pH favours growth of aquatic plants and all life forms that depend upon these plants.

This means a koi pond that is alkaline will support more life forms than one that is acidic.

Almost all lifeforms re-energize as air or water temperatures increase and koi or goldfish are no different. The urge to start life afresh is there for all living creatures and organisms. Some start to spring to life earlier than others after a prologed rest over the winter months in the koi pond


Don't stress over pond pH and Testing Koi Pond pH

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I will make a few very important points here which should be taken very seriously by anyone contemplating measuring pH in a koi pond and then TAKING ACTION based upon the measured result from testing the koi pond's water. If you test do it reliably... Interpet lead this pond water testing field of the koi keeping hobby

  1. pH of koi pond water will vary depending on time of day measurement is taken and especially if plants are in the pond. This means if you take a pH at 9am it will not be the same as a pH taken at 6pm. This single piece of information therefore must never be the information relied upon to make fundamental decisions
  2. pH is notoriously difficult to measure even in a laboratory with sophisticated instruments let alone in a koipond or fish pond using a piece of litmus type paper or a vial with coloured scales on it.
  3. If you must measure pond pH and this is a great part of the hobby then take the pond pH at the same time every day and plot the result on a graph. So now what you're looking for is not a single pondwater result but rather a pH trend in the pond water that you can use to sensibly consider a pH strategy.
  4. Very high pH in a koi pond is a serious threat to the well being of koi when levels reach about 9.5 because at this pH level ammonia which is a natural metabolic product of the koi and its existence becomes extremely poisonous
  5. It would be extremely rare for a koi pond to reach dangerous pH levels but could well occur in koi ponds with serious algae problems

My Very Best Pond pH Advice

Consider the testing of pH as a way of discovering the normal and natural variations that exist in every pond day in and day out. Tale a look at what happens in mid summer and the cold depths of winter. See testing of pH in a koi pond as another aspect of the fascinating hobby called Koi Pond Keeping.

While you're at it get yourself a complete testing kit and get into the habit of testing and recording your pond test results. Always remember one koi pond test is meaningless and potentially very dangerous to your koi and therefore your own stress level.

Most of all don't stress over pond "pH problems"... almost certainly there is no pond problem unless you added "stuff" you shouldn't have done in the first place.

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