As far as i know there are 2 different forms of iron sulphate, there is Ferrous iron (Fe2+) and there is Ferric iron (Fe3+) i think the one we would use commonly in our aquariums is FeSO4 (Fe2+) the other type as far as i know is Fe2(SO4)3 or Fe3+.
But if the ingredients aren't listed its probably risky to use in your aquarium, whats good for terrestrial plants may not be so good for your fishies.
I dont know how to calculate a dosage useing this either, but if its FeSO4 i think thats good to use but how much i dont know.
/www.gardendirect.co.uk/product.asp?...D=355&P_ID=4451
