We have 30-60% straight spirulina in our stock cultures. How can we prevent this from happening? What can we do to get the cultures back to predominantly spiral form?
How can we verify that we don’t have toxic contaminants and then still harvest the straight spirulina? Or is it necessary to start over with new culture?
Dr Cath, thanks so much for your very helpful reply. We have since obtained a new culture from a farm in Pretoria, and will be giving it more light, or rather are giving it more light. Last year we had a too-much-light event and overcompensated with shade!
From the time of purchase, the new culture has looked well, a nice bluegreen, and microscopically looks good with less than 1% linear forms, no bacteria, and no debris in the bottom. It is also growing, with no abnormal signs (ph, smell etc all good) However from the first day it never rises to the top of the culture medium. We only run the aquarium pumps during the day (intermittently). So in the morning we always check to see if the spirulina has risen to the top, which I understood is a characteristic of healthy spirulina. Is this something to be concerned about?
Second question, how often is it best to feed the spirulina for max growth leading up to harvest or to increasing the culture volume? We have heard/read different approaches from daily, to 3 consecutive days then rest 4 days, to 2x per week etc
Thanks so much for your kind and expert assistance! Karen