Why water quality is so important in a koi or gold fish pond

One of the best descriptions of the metabolism of a gold fish explaining the importance of water quality for koi was written by my friend William Kelly

Osmosis and koi and why they urinate continuously in the pond water.

This may sound like a mouthful (William does like to play with words and he is quite good at it too) but consider a cup of hot coffee with a spoonful of sugar at the bottom of the cup.

As the sugar dissolves into the coffee it is at its highest concentration closest to the solid sugar pile. This is perfectly logical.

This concentrated sugar then diffuses into the coffee and over time eventually once all the sugar has dissolved the sugar concentration in all parts of the coffee mug will be equal. This is known as equilibrium.

It is important to understand that at all times, all substances and properties (such as temperature and pH) in Koi or gold fish ponds seek to be at equilibrium. i.e. at equal concentration. It is the ideal natural state and there is a constant push and pull in order to get there. The fact that equilibrium very rarely happens is not important. What is important is that things try very hard to get there.

Osmosis is exactly the same process as diffusion. It is a term that refers specifically to water diffusion which is why it has a special name. Water will diffuse from areas of high concentration (i.e. pure water) to areas of low concentration (water with a lot of dissolved substances in it), in exactly the same way that the sugar dissolves into your coffee.

This means that even if the sugar decided to ignore physics for a while and not diffuse by itself, the water in the coffee would do the job for it and eventually the sugar concentration would be the same in all parts of the coffee due to the water diffusion process, which we call osmosis.

Now this is fine and well if you're a cup of coffee. Imagine now that you're a Koi. Your salty blood that is separated from the pond water by a membrane one cell thick is going to have a lot of water zipping across that membrane due to osmosis. Your blood is salty, the water is not, hence the natural osmotic process takes place.

If the Koi did not get rid of all this extra water through constant urination it would explode. So this means that the water in the pond is being constantly circulated through the Koi. Can you see how important water quality is to successful Koi keeping?

As every reader of my gazette should know by know there is no compromise when you install a fish pond be it for gold fish fish, koi, rudd, roach, blue gills or whatever. YOU MUST have a a bio filter. It is easy to make one yourself or if you cannot be bothered get a low cost one on line that works extremely well ... see below

William Kelly is the owner of Happy Koi ... visit his site

Water quality

Water quality is intricately and intimately linked to the health and the well being of Koi. In a natural pond, the constraints that face Koi keepers are nowhere to be seen. Koi have literally millions of litres of water that surround them, and they simply cannot produce enough waste material to in any way significantly affect the vastness of the lake or dam in which they reside.

A Koi pond by comparison has a much, much higher fish stocking density. The wastes that Koi produce become extremely significant since they are not diluted by nearly the same volume of water as in a natural environment.

Good water quality does NOT mean water clarity (think about any dam or lake). However, it is possible to have good water quality AND good water clarity.

An excellent article by William ... places the mysterious and invisible aspects of water quality into context for all of us.