Our Rust Preventer is a highly concentrated, all inclusive irrigation treatment blend that works in a variety of iron and mineral hardness levels.  The effective dosage rate for SPER Rust Preventer is typically in the range of 1 : 100,000 meaning one gallon of Rust Preventer can generally treat 100,000 gallons of irrigation water. For larger commercial systems, this means this 30 gallon drum will treat 160+ well hours (based on a 80 GPH irrigation pump). If you irrigate 8 hours per session & 3 days per week, you will get 21+ weeks of treatment with this single 30 gallon drum.  Higher iron levels will require additional treatment for adequate iron control.