FREE tds meter (orders over $50) OR FREE Shipping (orders over $150). Use code “FREETDS” or “FREESHIP” in the discount codes section of your shopping cart at https://Airwaterice.com (offer expires 6/30/17). 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. Stay TDS free with our RODI experts. Call 772-461-0256 or email sales@airwaterice.com to talk to a RODI specialist today. As always Happy Reefing, your friends at Air Water & Ice