I bought the product as 'Sprint 330' at a local garden store, here in Jackson, Mississippi. They sold it in 5 lb. lots, $46.00. Needless to say, it is more than I will ever use in my lifetime. I think Ciba has changed the name and is now selling it as 'librel Fe-DP'. I dissolve 1 level teaspoon in 391 cc of water to get a stock solution. Adding 1 ml of the stock solution per gallon of tank water gives you 0.3 mg of iron per liter. If you don't have a graduated cylinder for measuring water, add one level teaspoon to two cups of water. That is pretty close. Some kind of fluffy stuff likes to grow in the stock, and so I either store it in the refrigerator or heat it to boiling to sterilize it.