sounds absurd to me unless it was for a saltwater reef tank as most corals need pure water to survive. then i understand some people may not have an RO water unit at home for their reef tanks. however fresh water can be adjusted if you know what to do or add. water changes, good amount of flow, and filter media all work to keep your water healthy. just out of curiousity how much do they charge?
"The perfect man uses his mind like a mirror going after nothing, welcoming nothing, responding but not storing. Therefore he can win over things and not get hurt." -Chuang Tzu