If you have not taken the steps necessary to add oxygen to the water in your pond, the carbon dioxide levels may be higher than you think. If they are, then the chances are that the concentrated levels of carbon dioxide in your fish’s blood streams may also be high.
You see carbon dioxide is more soluble in water than oxygen. In fact oxygen levels in water become saturated at 9 ppm at 68o F where carbon dioxide becomes saturated in water at .5 ppm. In comparison to blood, the saturation levels are pretty close to being the same.
Fish will start to have problems breathing when saturation levels of carbon dioxide reach 5 ppm. I bet you did not know it, but for every pound of oxygen a fishes breathes in, it exhales about 1.38 pounds of carbon dioxide. That ratio alone puts the water oxygen levels at a deficit.
So what can you do about it? Well remember we talked about proper pond aeration? That is correct. Pumping air into your pond will increase the oxygen to carbon dioxide ratio in your pond water and make things a heck of a lot easier for your fish.
There is also a by product of proper aeration. As the air you pump into the water floats to the surface in the form of bubbles and pop, there is a gas exchange going on. This is where carbon dioxide is released in the process which is good fro the pond.
So basically, it really is as simple as that. I bet you were thinking this was going to be all complicated or something huh? Well there is one more small detail that you might be interested in.
For those of you that have an indoor pond or store your fish in an indoor pond, you need to think about where all that diffused carbon dioxide goes after it leaves your pond. Think of all of your family members plus yourself exhaling carbon dioxide.
If you combine that along with what is expelled from the pond, you too could find yourself in danger. You might consider some sort of air ventilation to expel the carbon dioxide outside where it won’t be harmful to you indoors. More elaborate systems could include a degassing column.
Degassing columns will strip the carbon dioxide from the expelled gas and return fresh outdoor air back into the closed environment.