CSM+B vs flourish
I recently got my first bag of CSM+B. The recipe is 1tbs in 250 ml water, then 1ml solution for every 10 gallon, dose every day. The recipe also says this solution is almost as strong as flourish (0.39% iron). Now I am a bit confused. The direction on fourish bottle says 1-2 ml for 50 gallon, once or twice a week. Its dosage is much smaller than CSM+B. Am I missing anything here?
Also, does anyone know the reasoning behind the CSM+B solution/dosage? I know the target is to maintain 0.1ppm iron level in tank, but I don't know the calculations. Can anyone show me how they get those numbers? Thanks.