My spirulina is yellow/pale green after a few weeks. What's wrong?

Spirulina changes color when stressed. Color issues when growing spirulina include:

– Not treating the water with Spirulina Food before adding it to the culture

– Temperature outside of normal ranges 18 – 37 C (65 – 98 F)

– Light outside normal ranges of 300–3000 lux

– Not the proper nutrient mixture

- pH is below 10 (add baking soda!)