When you discuss the use of ozone on an aquarium you will generally wind up at one of two conclusions; it sounds expensive, complicated, and dangerous for a result I can get with carbon or it's the best thing since sliced bread. Those who have never used ozone on an aquarium usually balk at the idea while those who have are generally very impressed with the result. 

The truth of it is, ozone is a very effective treatment for water and has been used as a disinfectant for drinking water and wastewater processing for decades. In an aquarium, the biggest known benefit is a level of water clarity that is difficult to achieve otherwise. The science of oxidization and how ozone reacts on a molecular level also suggests there are a variety of possible proxy benefits too including breaking down toxins and reducing the presence of bacteria, viruses, and algae - more on that below.  

Ozone Molecule
Ozone Generator

What is Ozone and Why Should I Use it?

Ozone is a relatively unstable gas molecule containing three oxygen atoms. When used in water treatment, ozone gas is created and injected into the water where it will have an oxidizing effect on the molecules it comes in contact with. It can be a very effective disinfectant but also help to eliminate both odors and coloring agents that exist in the water.  

Your aquarium can benefit aesthetically from this ultimate water clarity but also the removal of coloring agents ensures optimal light penetration. Many hobbyists also report the reduction in nuisance algae growth and believe the ozone breaks down harmful toxins, bacteria, viruses, and even parasites.

While the main benefit of water clarity is easy to see with your own two eyes, the sterilizing properties are still somewhat unexplored or simply not yet calibrated to the point of being widely accepted. The amount of ozone you need to kill various organisms and break down specific contaminants is unknown and the residual effects thereof are just not widely documented by hobbyists. It's something to consider but don't rely upon ozone as a means of killing off an outbreak of Ich or stopping an infestation of hair algae. 

Ultra Clear Water

Doesn't Carbon Do The Same Thing as Ozone?

While carbon can help remove odors and get rid of yellow-tinted water, ozone is just more efficient. Activated carbon becomes exhausted and must be replaced on a regular basis while ozone is always working and doesn't require regular replacement of media. Once set up, ozone injection is automated resulting in a very consistent level of ultra-clear water that carbon alone cannot achieve.   

Activated Carbon Media Bag

Is Ozone Safe To Use In My Home?

While ozone gas itself can be dangerous and damaging to your lungs, proper use of ozone in your aquarium poses minimal risk. The amount of ozone being created is controlled using an ORP monitor. The gas is directly injected into an enclosed reactor (protein skimmer) where it will immediately react with the water and won't be directly released into the surrounding air. The shelf life of ozone is very short and any residual ozone that might escape can easily be absorbed using a bag of activated carbon.

How to Install an Ozone Generator On Your Saltwater Aquarium

Shopping List
Ozone Set Up Diagram

Corona discharge ozone generators use electricity to create ozone and they are not complicated to set up or maintain.

  1. The air first passes through the air dryer where moisture is removed.
  2. The dry air then goes into the ozone generator where it comes in contact with electricity which creates the ozone.
  3. The ozone exits the generator and goes directly into your protein skimmer where it reacts with aquarium water.
  4. The ozone gas is contained inside your protein skimmer and if any residual ozone exists, it will exit through the top of the skimmer where it will come in contact with a bag of activated carbon for adsorption. 

The ORP probe monitors the ORP level in your aquarium water and will turn the ozone generator on/off automatically based on a set ORP level.

Oxidation Reduction Potential (ORP): The ability of the water to break down waste and oxidize contaminants. The higher the ORP, the higher the potential to oxidize pollutants. 

Injecting ozone into the aquarium water will increase ORP levels and the more ozone you add, the higher the resulting ORP level. We use ORP to monitor how much ozone is being injected into the aquarium. The target ORP levels in a saltwater aquarium with ozone are generally set at 300-350 mV, never going above 400 mV.

You adjust the amount of ozone using the dial on the generator with the ultimate goal of using as little ozone as possible to maintain clear water. As a starting point, inject 15 mg/hr of ozone per 25 gallons of aquarium water. It will take a few days for the ORP readings to stabilize, do not make large or quick adjustments to the ozone injection rate. 

Ozone Generator

FAQs and Tips For Succes

  • Ozone will break down various types of plastic and tubing material; always use ozone-resistant tubing and Kynar fittings to connect to your protein skimmer
  • Check to see if your protein skimmer is rated for use with ozone. Skimmers made using acrylic and/or PVC are generally ozone compatible but check with the manufacturer. Using inexpensive protein skimmers dedicated to ozone injection is an alternative route to avoid degrading more expensive protein skimmers. 
  • You can connect the ozone tubing to your protein skimmer's air silencer inlet port, airline port on the venturi fitting, or to a dedicated ozone injection port if your skimmer has one. 
  • The suction created by the air injection port on your protein skimmer is actively pulling air through the air dryer and ozone generator.  The ozone generator itself is not an air pump and will not "push" ozone gas out of the generator unless it's connected to a working protein skimmer.
  • Mount the ozone generator above the water level to avoid the backflow of water into the ozone generator; the use of a Kynar check valve is recommended.
  • Mount the air dryer in a dry location, outside of the tank stand to avoid rapid depletion of the desiccant (air dryer) media. 
  • The presence of moisture in the air can reduce ozone production by as much as 50% which is why a desiccant is required. 
  • Air dry media will change color when it's exhausted but it can be recharged in the oven. Bake desiccant silica beads in the oven at 300° F for 3 hours to recharge.
  • The presence of ozone may or may not affect your protein skimmer's performance. 
  • There are different types of ozone generators on the market, always reference the manufacturer's instructions for proper installation and operation. 
  • IF YOU SMELL OZONE, unplug the ozone generator, open a window and replace the activated carbon media.
  • You can put your ozone generator on a timer so it only operates at night.