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CO2 Generating Substrate

2205 Views 1 Reply 2 Participants Last post by  Diana
I was wondering if you had a high density of tubifex worms, like approaching the sickening density of those sewer slime monster videos, then would their respiration result in CO2? Also, consider that I have an undergravel filter attached to a powerhead. I'm thinking the water being pulled down will oxygenate the tubifex worms, causing them to release CO2. Is that feasible?

Also, I encountered this thread on CO2 generating substrate recipes:
Cheap Sand-based CO2 Generating Sub

The guy says he has tubifex worms, but that's not where the CO2 comes from. Also, he doesn't have an undergravel filter. What generates the CO2 are marble chips in the substrate. I'm thinking that the additional flow of an undergravel filter would cause the marble to deteriorate slightly faster? Does this person's idea even make sense? Do marble chips release CO2?

BTW, I currently have blackworms in the substrate. They don't seem to produce enough CO2 to promote plant growth. I'm guessing the tubifex worms can breed more densely, enough to become those disgusting sewer masses. If your substrate was half gravel/sand, half tubifex worms, with fresh water constantly being pulled downward through it, would their respiration contribute a significant amount of CO2?
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By the time you had enough livestock of any species to generate a serious amount of CO2 these animals would also be producing toxic levels of ammonia.
Marble is mostly calcium carbonate and magnesium carbonate. Coral sand, oyster shells, limestone rocks and similar materials are also calcium carbonate and magnesium carbonate.
When these materials are under water, and the water is acidic, low pH, these materials break down and add their minerals to the water. Levels of calcium and magnesium (GH) rise and carbonates (KH) rise.
Yes, there is a reaction between carbonates and CO2. As the level of carbonates rise some get changed into CO2. But this is not a significant source of CO2 in an aquarium. The reaction is rather slow, and the CO2 off gasses or can be used by the plants so fast that the CO2 will not build up significantly. I know 'gets used by the plants' is the goal, but the amount is so low it almost does not count. In the mean time the GH and KH are rising toward levels that will make the tank a good home for rift lake fish, live bearers and many rainbow fish. This is fine, if these are the fish you want to keep, but if your goal is Tetras, Rams, Rasboras, Cories and many similar fish, the water is too hard for them.
The very fact that the water has a high KH shows that not much of the carbonates become CO2.
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