Not an expert but don't think that you need to be to see that you don't get to the algae in product called "True Algae" until the 6th, 7th, and 8th ingredients. Overall it doesn't look much different than most other general fish foods in terms of ingredients (other than they promote some organic certifications). That's not to say that it's not good food. Should be fine to feed. Very similar to most other general tropical fish foods.
If you're actually looking for a true mostly algae product to feed there probably are some better options. I supplement some of my algae eaters with the Omega One dried seaweed sheets. It has one ingredient - dried seaweed (aka macroalgae).