all about ozone

Ozone is a naturally occurring, water-soluble gas and oxidiser. It can control many common bacteria and deactivate viruses. So should Ozone feature in your Koi pond set-up?

How Ozone Works

When Ozone comes into contact with waterborne pathogens one of the three Oxygen atoms detaches itself from the Ozone molecule and then attaches itself to the pathogen. It oxidises it and so destroys it. Ozone is so powerful that the tiniest amounts will offer an effective germicidal action whilst leaving no toxic by-products or residues in the water.

What is Oxidation?

Oxidation is the process that causes metals to rust or fruit to turn brown. The process damages cell structure and so kills simple organisms quickly. Oxidation is how beneficial bacteria remove ammonia and nitrite from ponds by converting the ammonia to nitrite and then to nitrate.

Will Ozone Affect a Bio-Filter?

Ozone will kill harmful bacteria when they pass through an Ozone stream in a protein skimmer. However, beneficial bacteria do not pass through the stream as they live on the filter media. Some will be free-swimming and so will be killed by the Ozone, but this process is balanced by the fact that the good bacteria grow more rapidly in an ozonised system as the entire pond system is cleaner and better aerated.


Ozone will kill algae even if they don't pass through the Ozone stream, as the ozonised environment leaves algae more susceptible to oxidation.

Will Ozone Harm Koi Stocks?

Ozone helps to eradicate simple organisms but is not harmful to more complex organisms such as Koi carp. The Koi never come into direct contact with the ozone stream and any residual gasses are not transferred to the pond water, they are expelled into the atmosphere. It has been argued that Ozone creates a sterile pond environment but there has been no scientific evidence found to support the suggestion that Koi's immune systems can be damaged by pond disinfection via oxidation. Ozone helps to create a more natural environment in a Koi pond similar to that in a river where the level of bacteria is generally much lower. Marine aquarium enthusiasts have been using Ozone systems for many years and see only improvements in their stock's health. Ozone represents no danger to human health if handled correctly.

Creating an Ozone System

An Ozone system does not replace your conventional filtration system, it should be used in partnership with it and will ensure that it is more efficient. You can still use chemicals in your Koi pond to address parasites but you must switch off the Ozone generator when you do this as it will destroy the chemicals. Perhaps it is time to consider using Ozone in your Koi pond if you haven't done so already. If your system is correctly installed it could provide the pond environment you need for your Koi to really prosper.

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