Add enough mix to the tank every day to keep the Fe level at about 0.1ppm (the exact amount will have to be determined by experimentation, but 3mL per 100L tank water is about right for a tank with rapidly growing plants).
(the exact amount; to be determined; by experimentation) (3mL per 100L tank water; is; about right)
the exact amount 3mL per 100L tank water
to be determined is
by experimentation
about right