Most algae wafers aren't even very herbivorous. They often rely on a lot of shrimp and fish meal with some recognizable plants thrown in. I like new life spectrum formulas for that reason. My 2mm sinking NLS algae pellets are "Algae; chlorella, ulva seaweed, red seaweed, kelp, spirullina, wakame seaweed, whole antarctic krill, whole fish..." and on to some flours, plants like alfalfa, and a vitamins and minerals.
versus hikari sinking wafers " fish meal, shrimp meal, wheat germ meal, wheat, flour, soybean meal...."
and Hikari algae wafers which specifically say ideal for algea eaters "fish meal, wheat flour, wheat germ meal, starch, dried seaweed meal, dried bakery product, dehydrated alfalfa, brewers yeast, soybean meal, fish oil, krill meal, spirullina, garlic..."
Take a good look at your algae wafers/pellets if you truly want to add more herbivorous options to any tank. Many are krill, fish, or shrimp first with some plant matter and maybe one algae thrown in.