Tol Watertechniek - Specialist in waterbehandeling en ozonsystemen +31 (0)61 245 40 88

Ozone FAQ

On this page you will find answers to frequently asked questions and give our idea on persistent misunderstandings about ozone. This mainly relates to ponds because here are most misunderstandings about ozone.

A redox value of 350 ~ 400 mV is a good value for ponds.
# This value is actually too high for a pond, 275mV is a better guideline.

Using ozone makes my pond sterile.
# To get a sterile pond with the usually advised amounts of ozone is virtually impossible. When misused  there may come ozone in the pond water which has a negative effect on your fish. The consequences may well be confused with a sterile pond.

Ozone breaks down ammonia or accelerate this process.
# If this really were true why does everybody which uses ozone still has a biological filter? The answer is simple, the amount of ammonia degrade by ozone (converted is a better description) is practically zero. Accelerating the conversion isn’t true neither.

Ozone breaks down nitrite or accelerate this process.
# Nitrite is converted to nitrate by ozone, without the use of oxygen.

Ozone makes my biological filter function better.
# Because the oxygen consumption used for oxidation is decreased by ozone, more oxygen will be available for the biological filter.

Ozone adds extra oxygen to the water.
# Yes and no. The injected ozone will fall back to oxygen and therefore it is oxygen increasing. The same effect can be reached much cheaper with an air pump. An important advantage is that ozone will decrease the oxygen consumption of your pond because it oxidizes substances, which otherwise would require a lot of oxygen.

Ozone helps against algae.
# The average ozone installation on a pond will do little against algae, the residence time is simply too short. In order to kill algae a minimum residence time of 4 ~ 5 minutes is needed.

I can place a UVC lamp behind my ozone installation to destroy residual ozone.
# This is possible but we strongly recommend to don’t do this. UV light causes ozone to converted into hydrogen peroxide and OH radicals. Both substances remain long in the water and are very harmful to your fish. If you use a good ozone there is no or little residual ozone in the water, so there is no need to destroy it.

There is 1 gram of ozone per 20 m³ of water needed.
# This depends on many factors, the performance of your ozone reactor and the ozone concentration are the most important ones. With a bad ozone reactor,1 gram of ozone is not enough, with a good ozone reactor is 1 gram enough for 50m ³ of water.

1 gram of ozone, ozone is 1 gram
# This might seem strange, but read the following piece of text, then you will understand what we mean.

There are the most beautiful numbers mentioned on ozone generators, but are these numbers true? Is one gram ozone really one gram?? Under what circumstances is this value measured, and is it measured at all?

Most manufacturers unfortunately don’t list the measurement conditions under which the ozone output is measured, so this value is of no use. However, the measurement conditions make a big difference! The ozone yield of many (budget) ozone generators is measured with a dew point of the supply air of -40 degrees. With a standard air dryer powered by an air pump you will have trouble to reach a dew point of +5 degrees. This difference of 45 degrees causes  that your ozone generator doesn’t deliver the mentioned 1 gram of ozone but more likely 0,5 gram or less.
Another important factor is the amount of air needed to make 1 gram of ozone, this determines the ozone concentration. This value says something about how easy the ozone will exchange with the water.
A good ozone generator will need between 5 and 8 liters air (dew point 0 degrees) to generate 1 gram of ozone per hour. There are also ozone generators which need for the same amount of ozone over 20 liters of air, the ozone concentration is less than a factor of 4! This means that your ozone reactor need to be much larger to reach a similar result!

You see, 1 gram of ozone is not always 1 gram of ozone.