whatever does not kill us, makes us stronger? LOL I think it might be OK if you rinse it very thoroughly - in a way it might be like beer-brewing. In olden times, the quality of water was not easy to assess - it might make you sick. But beer, if it tastes good, is proof that conditions have been achieved for fermentation and therefore, bacteria could not be present in significant numbers (else the beer would sour!). Maybe a healthy spirulina population in a pond is like that? I suspect it is true, but I have been unable to develop a spirulina culture so far (and partly from lack of serious effort).