Aquarium help > New tank syndrome & NH3 > reducing ammonia NH3 levels
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    We know high levels of NH3 (ammonia) is harmful to fish in the aquarium or pond but reducing them can often be a problem. Please follow this link to understand what are safe NH3 levels.

    All aquariums should have a biological and or chemical filtration to control ammonia. Biological filtration uses bacteria colonies to convert ammonia to less harmful substances. Chemical filters remove the ammonia and lock it away; the most common material is zeolite. If you see sudden spikes without a change in stocking or feeding levels than it is likely that either of these methods has failed, allowing ammonia to rise to unacceptable levels; a chemical additive or water changes is a good ways to reduce free ammonia levels.


    The root cause of high NH3 it can vary but usually it is worth checking the following:


    1. make sure you are not over stocking or stocking too quickly. Also see New tank syndrome.
    2. make sure you are not overfeeding.
    3. make sure that a fish has not died in the pond or aquarium.
    4. make sure that your filtration is working correctly and is not too small
    5. ensure that water used for changes has a similar pH, else  NH3 may be converted from NH4 with a pH increase.
    6. filters might have been over cleaned and the beneficial bacteria colonies killed or removed.


    Here are a few common ways to remove or control ammonia:

    Short term (instantly remove ammonia)

    1. water changes - this is by far the fastest and most reliable method but care should be taken not to stress the fish or add unsafe water.
    2. ammonia-removing chemicals - there are many ammonia-removers on the market but they are no magic cure. You have ammonia because something is wrong; using chemicals is not a long term solution.

    Long-term management

    1. increasing biological filtration - this could take longer than the two above, so might need to be used in conjunction with them. Usually, it involves adding more filtration, especially with a high flow and media with a large surface area for bacteria to colonise. Another way is to encourage bacteria to colonise much more rapidly. A few tips can be found here.
    2. adding bacteria - you can also buy beneficial bacteria in a bottle and these are ideal for reducing ammonia. These can be used to seed a new aquarium with good bacteria and should ideally be used in conjunction with the point above. Old mature aquariums can also benefit from boosting the colonies of good bacteria. An example of such a product is linked below.

    fritz-zyme range.jpg