BillD
Aquarium Advice Addict
This is a good discussion. Densely planted tanks can remove most of the CO2 in a tank under the right conditions, such as intense light. The purpose of injection is to increase the amount of available CO2. Since CO2 dissolves easily in water, injection works very well.In a CO2 injected tank, you don't want a lot of surface agitation which would hasten the gassing off of the CO2. So, the idea of low water movement has merit in an injected tank. In a non injected tank, if the plants use up CO2 faster than it is being produced , than, water movement will help replenish it via the surface to air interface. You can not increase the concentration of CO2 in the water above what the concentration is in the air. By the same token if you were to vigorously agitate water that has been injected with CO2, you could only gas it off until it reached the concentration in the air.
This is basically what is happening with the oceans. The high concentration of CO2 in the air is getting into the ocean water and lowering the pH. This type of occurrence is probably amplified at the shore where wave action is often intense.
I too, have grown thousands of plants (no exaggeration) in a tank with air powered sponge filters and no ferts. I can post pictures if you like
This is basically what is happening with the oceans. The high concentration of CO2 in the air is getting into the ocean water and lowering the pH. This type of occurrence is probably amplified at the shore where wave action is often intense.
I too, have grown thousands of plants (no exaggeration) in a tank with air powered sponge filters and no ferts. I can post pictures if you like