Hypothesis Carbon dosing for bacterial growth in planted aquaria

Do not take as truth until confirmed


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  • Oct 29, 2022
    Miami, FL
    Back in 2015, I did a ScapeFu podcast episode on Dosing Vinegar in Your Aquarium. It was based on the carbon dosing being used in reef aquaria but hypothesizing that it could have some benefits in the planted aquarium too. I still think it does but my thinking has evolved as to why. This is why this posted is marked as a "hypothesis" and should be taken as such instead of truth.

    NB, I am not talking about adding a form of inorganic carbon such as glutaraldehyde or Excel for photosynthesis. Although, a byproduct of increased bacterial activity is more CO2 in the water that is expelled by the bacteria. Increasing bacterial populations in reef aquarium have been shown to decrease the aquarium's pH and it's thought to be the result of the metabolism of the bacteria.

    • We are starting to understand that bacteria do more than just uptake nutrients. The compete with other organisms, some of which we want to limit, such as diatoms and dinoflagellates.
    • They may inhibit some types of algae as algae spores will not have a place to colonize.
    • They are very beneficial in converting waste in the aquarium and decreasing DOC. Many waste treatments facilities add them as part of their processes.
    • There may be added benefits within the substrate ecosystem. More to be hypothesized here.
    • Work with plants to absorb nutrients and assist in outcompeting algae. Especially useful during ammonia spikes as they will uptake the ammonia quicker than algae.
    • May work at producing ammonium (NH4) in the planted aquarium thereby creating a readily available (and preferred) for of nitrogen for plants. See The Effect of Caffeine on the Bacterial Populations in a Freshwater Aquarium System.
    Things to watch out for:
    • Too much carbon may cause cyanobacteria in the aquarium. The risk differs with different types of carbon addition.
    • Oxygen can be quickly depleted so supplemental oxygen via an air stone is recommended at the beginning.
    • Some think that it may cause BBA in the aquarium. I am not in this camp as I never experienced BBA while I was dosing carbon. All aquariums have heterotrophic bacterial populations.
    • The bacterial will take up nitrate and phosphate so you must be supplementing these and testing so that they don't bottom out. Not too dissimilar to the phosphate uptake when using soils for substrate.
    Does anyone have any thoughts on this, even theoretical? When I set up my next planted aquarium, I will experiment with dosing carbon right from the beginning and see if I see any beneficial response during the startup phase.