Home Forums Growing Spirulina Self regulating spirulina?

This topic contains 2 replies, has 3 voices, and was last updated by  Elliander 7 months, 1 week ago.

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  • #2454


    I have only access to fish tank equipment which means that the pH I can get is only 8,5. My question is why all the tutorials say that I should wait until it reaches 10 before harvest. Does spirulina regulate the pH by itself as it grows or what am I missing?

  • #2628

    Henri Lentonen

    I think the point is that high pH makes the culture sterile from pathogens.

  • #2695


    High ph is only one factor. It is generally true that very few organisms will grow in water that alkaline though.

    In one of my experiments, where I used the absolute minimum required to test phototoxicity limits, I used 64 half drops spirulina culture in one 20 oz container with a constant light source and aeration in the an incubation room which was also used to culture human pathogens. A a contaminant became apparent and began to grow faster than the Spirulina, and was visible to the naked eye. However, just a week later there was no trace of anything other than Spirulina either to the naked eye or the microscope. At some point Spirulina uses it’s numbers to aggressively destroy other bacteria in it’s environment, which is an additional layer of protection.

    I also read studies that others conducting involving viral contamination, where the Spirulina halted all viral replication. This included Influenza, the common cold, herpes, and HIV, just to name a few I am aware of. To be clear, Spirulina didn’t destroy the virus, it just prevented replication. Regardless, it’s an important detail because it means if a virus found it’s way into the culture it’s not going to be capable of reproducing to a point of being an actual health risk and would likely be destroyed by the environment. However, there would need to be a very dense culture to have this property.

    The only real potential risks that I am aware of: Other kinds of cyanobacteria which produce cyanotoxins, which needs to be tested for and is one reason why I use reverse osmosis water. In Illinois, where I grow Spirulina, there was a situation of cyanotoxins in drinking water due to a bloom of dangerous cyanobacteria. Although no living cells made it through, if cyanotoxins ended up in my culture it could result in a false positive. Then there’s a kind of virus that has figured out a way around cyanobacteria defenses by waiting until the cell is dead and then reanimating it (look up zombie cells) but I don’t think it could really do that in a dense culture that is healthy. Neither type of risk is likely to occur in the general grower setting.

    I have also observed that a completely dead culture can be reinoculated without risk, provided that you wait until the culture is mature before harvesting from it. You can also leave a culture sitting without for several months without adding anything to it provided you don’t harvest from it, meaning it can sit and wait until you are ready, but what’s actually happening is that cells are recycling as they would in nature and it can taste more bitter due to dead cells in the mix, but still not bad.

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