Many of us do not know much about nitrogen. We might remember from our school days that the air we breathe is nearly 80% nitrogen and we may hear the odd gardener talk about getting some nitrogen into the soil. But after that the chances are we know very little else. So where does nitrogen fit into our thinking on our Koi filter and the pond it keeps clean. Actually it has a lot to do. Of the four basic cycles of life the nitrogen cycle is the most complex. That being the case we will not bore you with all the little details which we do not really need to know as we look after our Koi filter. But a basic understanding of some of the details will help you manage your pond with a much better understanding.
Part of the Air we Breath
In the world in which we live and at the temperatures that are part of life on earth nitrogen does not react with everyday common chemicals. Under these conditions it is considered an inert gas. We breath it with every breath we take.. While we absorb the 20% oxygen into our blood stream in our lungs, we do not absorb nor do we need the other 80% of nitrogen which is expelled as we breathe out. (However under extreme pressures nitrogen can be forced into the blood stream which is what happens when a diver gets the ‘bends’.)
A Basic Building Block of Life
Nitrogen is found in all living things. It forms a part of proteins, and other life-sustaining foods and chemicals. However it does not become a part of any living organism in its natural state, it has to be reduced or ‘fixed’ in order to be useful for plants and animals and this is usually done by bacteria. This bacteria can live freely in the soil and is often associated with roots and leguminous plants. The plants are then able to take ammonium ions and from these ions are able to form proteins and other life-sustaining compounds.
Plants are able to feed on what are known as nitrates. This is an important factor in understanding the role of nitrogen in animal biology. We will not get into the chemical composition of nitrates except to point out that they obviously have a large component of nitrogen in them. The ability of plants to absorb this form of nitrogen plays an important part in the role of nitrogen in the living world and as you will see this is the final stage of the work going on in your Koi filter.
Animal biology, which includes our Koi, is absolutely dependant on nitrogen-containing amino acids which are used to build proteins. As we introduce plants, fish and fish food into our Koi pond we are setting up an ecosystem which has at its base the natural nitrogen cycle found in nature. The heart of this ecosystem is your Koi filter.
The Nitrogen Cycle
Lets follow this in our Koi pond. We feed the Koi food which contains proteins and other nitrogen containing foods. This food is the source of energy for the fish. The fish take in oxygen from the water and expel carbon-dioxide through their gills. However their organic solid wastes excreted into the water form ammonia as does rotting uneaten food, and any other rotting material such as dead fish or leaves etc. In nature this is not an issue but in a closed system such as a pond ammonia levels could build to the point where the Koi could die in their own waste products. This is where the Koi filter comes into play. Without the filter ammonia causes swelling to the gills and in time the fish will die for lack of oxygen.
Inside the Koi Filter
The Koi filter has as its base a fibrous material which serves to filter out the solid matter being pumped from the pond to the filter and back out to the pond. What is often not appreciated is that bacteria grow on this fibrous material and they grow with the rising levels of ammonia within the pond. After you start your pond filter system within few days the levels of bacterial will grow and feed on the ammonia giving off nitrites. Kits to build up the bacteria levels can be purchased but the colonies will grow naturally but a little more slowly, and let face it most of are impatient. Nitrites are not quite as harmful to the Koi as ammonia but they are bad enough. They are harmful and poisonous and are fatal to Koi in that they act on the haemoglobin in the blood as does carbon monoxide in humans.
Testing for the presence of ammonia and nitrites is important particularly in the early stages of setting up your Koi pond and getting your Koi filter functional. You are working towards establishing a balance of having enough filtration to handle any waste being produced by the Koi. Behind this natural filtration process are two further issues that while not part of the nitrogen cycle itself are very important if the nitrogen cycle is to continue successfully. The pond water needs to have adequate oxygen levels and normal pH levels. The bacteria require oxygen to convert ammonia into nitrites and your pond design should have ensured that sufficient oxygen is being dissolved into the water.
Nitrites and Nitrates
Within the ecosystem you have built within your pond and the Koi filter a further group of bacteria now go to work on the nitrites. They too need oxygen. They convert the nitrites into nitrates which are no way near as poisonous to the fish as ammonia and nitrites. However nitrates if they are allowed to increase in concentration will also prove fatal to the Koi. Testing for nitrates is not as urgent but it is just as easy to test for all these levels at the same time, ie., pH, ammonia, nitrites, nitrates. Until you are satisfied that you have achieved a good balance in your pond these tests should be done on a very regular basis.
Good Pond Design
We now come back to the plant life in your pond. As I said earlier plants are able to feed on what are known as nitrates. This is where good pond design has allowed for sufficient plant life to grow to absorb all the nitrates being produced. Since Koi can be somewhat destructive of plant life a two stage pond system is an ideal design feature that will allow for sufficient plant life to as were deal with the nitrate issue. Set up an upper pond for plants to deal with nitrates. Have a waterfall to provide for oxygen as it exposes the water to the air. Your second level can carry the Koi together with some plants for shade and nibble food. Pump your water from the lower pond through the Koi filter containing all the bacteria to the upper pond and you are setting up an ideal ecosystem. One final advantage of this system is the lack of algae. Algae also feed on nitrates and an excessive amount of algae is a positive indicator for the presence of nitrates. Get this design right and you do not have to battle with algae.
Without sufficient plant life, and this is not always possible, you will need to become involved in changing some of your water also on a regular basis. This is another issue and we will not deal with it in this article except to say that you should not attempt to change large percentages of your pond water at any one time and if your water source is town supply you may need to use a dechlorinator depending on the amount of chlorine in your town water.
Your Knowledge of Nitrogen
Most of us grew up with the knowledge that all animals need air/oxygen to live including fish. What perhaps we did not learn is the wondrous ways of the nitrogen cycle. It is invisible but if it does not operate in your Koi filter and pond your Koi will not survive. Nitrogen has a lot to do with your Koi filter! Now you know why you need to test for ammonia, nitrites and nitrates and keep an eye out for your pH while you are doing this. It would be nice to test for oxygen at this time but this is a lot more difficult. Just ensure that you have plenty of aeration going on in your pond.
For more information visit https://www.koihowto.com for a whole lot more about Koi.
Originally posted 2017-04-19 17:54:54.