So I have a lot of time to think about aquariums but not much space to build one until after my wife and I buy a new house. This has lead me down several experimental rabbit holes as a fun way to pass the time.
My latest thought is wondering if its possible to simulate the natural process of co2 generation in an aquarium. I previously did an experiment (which failed
) where I tried to introduce elevated levels of co2 through dissolving regular air into an aquarium through a reactor. During the course of that experiment it was pointed out to me that co2 forms in streams and lakes etc through the decomposition of organic matter and through the dissolution of carbonic rocks. So can we do this in an aquarium?
My proposed experiment would involve a bucket that would be used as a reactor of sorts. In the bucket would be layer(s) of soil and carbonic rocks (limestone probably though obviously open to suggestions). Water would run through the bucket constantly. The soil would naturally decompose and the rocks being reactive would dissolve. Both processes would release carbon into an aquarium. If I also aerate the water I should get at least some bonding of carbon to oxygen.
Potential problems with this idea include but are likely not limited to:
1) Difficulty in generating enough co2 to be worth the effort
2) The limestone will raise ph and hardness
3) Potential for soil being spread throughout the aquarium instead of staying put in the reactor
If the experiment is successful then problem 1 is solved. For problem 2 it is my hope to balance the amount of soil to rock in the aquarium. Hopefully the soil can reduce the hardness and ph. It will definitely be a balancing act to have the right soil mix (peat moss added etc) to counter the ph and hardness while still allowing for the carbon to be released and bond to the oxygen. Problem 3 will be solved by making sure the flow of the water does not directly disturb the soil. Possibly using baskets to hold the soil and alternating that with baskets of rock? Or using the rock as a "cap" for the soil? Will need to play with the design of the rock and dirt reactor to figure out the best way.
In the end I am confident this could work somehow because it does work in the natural environment all the time. The issue to my mind is not if it can be made to work, but whether it can be made practical and work. If I need a dump truck of soil to generate 20 ppm of co2 in a 10 gallon aquarium then its not practical. If I can have a 5 gallon bucket of rock and soil to do the same, then its potentially something of interest.
To do the experiment I will need two 5 gallon buckets, a pump, an air pump, some plumbing parts, potting soil, and crushed limestone. I will also need some way to layer the limestone and soil. I would like a way that is easily removable such as baskets but I may settle for something simpler.
One 5 gallon bucket would act as my "aquarium" while the other would be my reactor. I would pump water from one to the other and back out again in a loop. I would also aerate the water along the way. After running it for a while I would test the water for co2.
Thoughts? Suggestions? I am very open to ideas on how to run this experiment. The creating and running of the experiment is fun for me so know in advance I don't think this is a waste of time even if it fails. If it works it would be pretty fantastic and the cost of running the experiment will be limited to buying some crushed limestone and maybe some plumbing parts as I have the other materials already.