I recently bought liquid chelated iron at a gardening store. Its called GREENOL. It is 3.64% Sulfur, .13% chelated copper and 6.13% chelated iron. (Also .10% chelated Zinc). Has anyone heard of this. I am not sure of the dosage to add to my tank. I have a 150 gln discus tank and do water changes every 3 days. Please respond! I really need to know how much to add!!! Thanx!! Bobby Brunner at aecom_yu.edu