Nitrogen cycle and fish pond filters: Understand the nitrogen cycle, get great pond water quality

The nitrogen cycle explains what happens in any koi pond or other type of fish pond when fish pond filters are installed. Understanding this nitrogen cycle in fish pond filters (more correctly nitrification) is key to the best water quality for your pond. Select and operate pond filters with this in mind.

Oxygen from circulating pond water is critically important to the nitrogen cycle. Koi fish food can contribute greatly to poor pond filtration Nitrogen Cycle Practicalities In practical terms fish pond filters are built to model the nitrogen cycle. Homemade pond filters can be as good as any commercial unit if the principles of the nitrogen cycle are understood and followed well and good biomedia is used. To summarise for fish pond filters to work or more correctly the nitrogen cycle to work the following must be true: The nitrogen cycle needs a source of nitrogen (fish secretions), it needs oxygen from a waterfall or air bubbler and it needs specific bacteria - naturally occurring The nitrogen cycle can only work efficiently if all these components are in equilibrium Nitrogen Cycle - Pollutants The first pollutant to occur in a pond containing fish is a chemical called ammonia. Ammonia will poison the fish unless removed in pond filters by specific bacterial biological processes collected together under the term nitrogen cycle – this is why fish pond filters are called biofilters. Ammonia pollution signifies the need for biological activity to clean up the water in any fish pond. In fact unless ammonia is present the nitrogen cycle cannot proceed.
	The first stage of a biofilter is designed to convert this ammonia into other nitrogen containing chemicals called Nitrites that are poisonous to fish and if not removed by further biological action in the next stage of the nitrogen cycle they build up and your fish die.  The final conversion in the nitrogen cycle involves converting Nitrites to Nitrates. This occurs simultaneously in the fish pond filter. Many of you will be familiar with the chemical term, Nitrates, since most garden fertilisers contain nitrates.  These nitrates tend to stay in the gold fish pond unless there are plants or if portions of the gold fish pond water are pumped out regularly.  Both types of bacteria operating within the nitrogen cycle need oxygen. These bacteria cling to all the surfaces inside the fish pond filters. It therefore should make sense that any homemade pond filters must allow for larger surface areas where the oxygen, the nitrogen chemical and bacteria can all contact each other at the same time.  In the absence of oxygen all the bacteria will die quite quickly and the poison levels will build up. How do you avoid this happening in fish pond filters? – easy just make sure your pump runs 24 hours per day 365 days per year thus providing the fish pond filter with life giving oxygen that is dissolved in the water. We can summarise the nitrogen cycle as follows:  Protein in fish food after digestion by the fish becomes ammonia that becomes nitrites and eventually becomes nitrates ( all these contain nitrogen). Two different but naturally occurring bacteria do all this work. Ammonia and nitrites are poisonous, nitrates much less so.  All this biological conversion takes place in a bio filter or pond filter and willl continue for ever so long as there is:  food, oxygen. bacteria Remember: In the first few weeks after a new pond filter is installed and until the nitrogen cycle is operating efficiently high ammonia concentrations can only be handled by changing large portions of pond water on an ongoing basis. Do not put too many fish in the pond and do not feed much until the nitrogen cycle is in some equilibrium state. The nitrogen cycle needs time to reach a fairly steady stage - some 6 weeks or so easily - and is critically important to your fish's living (or death) conditions. The clear message is whether you understand biofiltration or not you MUST have a biofilter or fish pond filter of some description operating in your garden pond. Some people refer to uv pond filters. You should note that the term uv pond filters or uv filters for water gardens refers to items NOT designed to purify water but to remove the pea soup appearance of pond water. uv filters for water gardens are covered in a different web site - see the ultra violet links. Pond filters with uv are however commonplace and can save a lot of hassle since it is normally simpler to install combined pond filters with uv than the two seperate components. Algae in koi fish ponds, koi pond algae control: please review our web pages on ultra violet light A few unusual terms used to find biofilter information Unusual terms to find information about biofilters make a pond filter ornamental pond filter mtbe trickling biofilter biological pond filter construction small sand filter for fish pond build biological filter building a filter for a pond filtration system for pond biological fish pond filters cyprio pond filters koi pond filter media home made pond biofilter fish pond filtering garden ponds water filtration cyprio filter foam building a fish pond filter how to make a fish pond filter build my own pond biofilter koi pond filter system build a biofilter make fish pond filters homemade biofilter little giant biofilter how to make a biological pond filter fish mate uv filter fish mate pond filters fish pond filtration systems pond biological filter build biofilter and pond water hyacinth biofilter scenic biofiltration system fish ponds pumps & filters