>>Is it difficult to grow. I have been told it can be grown
Spirulina is easy to grow. Did it for my M.S. back in 1984. However, too
much sun is actually NOT good. It bleaches the little buggers. Add a
little baking soda (sodium bicarbonate, 4 g/L) to a solution containing K,
PO4, SO4, Na, Cl, Mg, Ca, Fe, NO3 and micronutrients. Try the plant food,
it might work. Spirulina likes it salty and alkaline.