FREE TDS meter (orders>$50) & 10% OFF from ! A good TDS meter is our industrys BEST way to know when to change your membrane & DI resin. [Free TDS meter is offered for orders > $50.00, use code: ““FREETDS”” in the discount codes section of your shopping cart at Airwaterice.com]. All Delaware Reef Club members can get 10% OFF on every order by using code: 32379. You can pay MORE but you can’t get less than ZERO tds AND you know us, We have your filter pack! ALWAYS fresh, EVERY time. Want answers now? We are a family of humans that answer the phone! call us 772-461-0256 to talk to an EXPERT specializing in exclusively RODI for over 30 years OR shoot a email to sales@airwaterice.com. As always Happy Reefing, your friends at Air Water & Ice (offer expires 12/31/16)