Instructions
Purchase a test online from the AquariumGuys website to test the oxygen level in your aquarium water (see Resources).
Open the test kit. You will find an empty test tube and three vials of test liquids marked O2-1, O2-2 and O2-3.
Take the empty tube and fill to the line on the tube with your aquarium water. Dunk the tube in the water and then pour out any excess water above the line.
Use the O2-1 liquid by adding five drops to the tube. Swirl the solution gently for 20 seconds, but be careful not to shake it. This will provide a false reading by adding oxygen to the water.
Continue the test with the O2-2 solution. Add six drops and again gently swirl for 15 seconds. Let this mixture set for five minutes, if you have a saltwater tank, and one minute for freshwater aquariums.
Finish the test by adding six drops of O2-3 swirling after each drop for five seconds. Let stand for 30 seconds so the color develops.
Check the color by placing it on a white sheet of paper and then looking down through the tube. Compare to the color chart that comes with your kit for your oxygen reading. If you need more oxygen in your aquarium water, consider purchasing an air stone.
How to Test Aquarium Water Oxygen Levels
Fish need oxygen to live. Test the oxygen level in your aquarium water regularly so your fish can breathe and live happily. Most aquarium owners are not aware of a test for oxygen levels, but this simple test is available and should be a part of your fish maintenance program.