Most people using ozone know about gamma and how it is relevant to the various protocols of ozone therapy. However, the strength of ozone in water seems to be a source of confusion within the industry. In this article we will set the record straight and show how ozone in water is measured. You will better understand the differences between high strength and low strength ozonated water and how to better utilize your equipment to produce optimal concentrations.

Measuring Ozone

The ideal way to measure the concentration of ozone in water is PPM (parts per million). PPM measures how much ozone has been suspended (dissolved) into the solution. Gamma (mcg/ml) is how we measure the ozone gas produced by an ozone generator. Since some of the ozone bubbles to the surface of the water and escapes out of the exhaust (ideally into a destruct system), you can’t determine PPM strictly by the gamma output. If you’re pumping ozone gas at a rate of 100 gamma, it doesn’t automatically make the ozone in the water 100 gamma or 100 PPM. You can have a general idea based on the oxygen flow rate, ozone concentration, and volume of water, but we want the most realistic numbers. Let’s break down parts per million and do some real tests.

A PPM of 0.5 is typically considered a sterilizing agent. Higher concentrations can neutralize microbes with even higher effect. A good way to categorize ozone water would be as follows:

Low strength            0.5 – 1 PPM
Medium strength      1 – 5 PPM
High strength            5+ PPM

The chart below shows several different microbes and the suggested concentrations to effectively sterilize them.

Chart source: https://www.ozonetech.com/applications/water-treatment/water-disinfection-ozone/

Test Results

All of the water tests contained in this article were done with distilled water (0 TDS) with 0 ppm as the starting point. The water was room temperature at 70-71° F. The volumes and concentration of ozone will be noted in the examples below.

Equipment: PPM is determined using a good ozone PPM analyzer. For our testing we used the ATI Q45 ozone water analyzer and the Chemetrics SAM I-2019. We also used a 500ml water bubbler/humidifier combo. This is a borosilicate glass system with an Erlenmeyer flask and a glass stem that descends into the bottom of the flask. The ozone gas is pumped in and dispersed through the white fritted glass diffuser at the bottom of the glass stem.

Note: The glass diffuser is made from medium-coarse fritted glass, and these can have minor variations from batch to batch that can affect how efficiently the ozone is dispersed into the water. Because of this, minor differences in concentration can be expected (less than 5%).

Using 500 ml of distilled water we tested concentration in the water in both 10- and 20-minute increments.

This is more of an approximation of what you can get instead of an exact number. Things like water temperature, water quality (distilled, DI, RO, filtered, mineral, etc.), and ozone concentration can all affect the final concentration.