Dissolved Oxygen

Dissolved oxygen is oxygen that is in the water. To conduct a dissolved oxygen test you need the kit and your tank water. First you get about 25 ml of your tank water in the special cup, then take the glass tube and stick the skinny side in the cup in the ridges on the bottom and break off the tip. The water from the cup will go into the tube and the liquid will change from yellow to blue. Then you take out the tube and swirl it and wait 5 minutes. Then you compare it to the color card in the kit to determine your dissolved oxygen level. All fish can live in 5 mg/l and up but under that is when the fish start to lose oxygen and die. The dissolved oxygen level in my tank was about 1.5 so I added more plants and filled it with more water so the filter would continue to move the water which would create more oxygen. A small pond would definitely have a smaller D.O level than a large river because the river has flowing water and the pond's water isn't moving.