Today on BRStv, we have another episode of BRS 52 FAQ where we answer all of your frequently asked reefing questions from our popular 52 Weeks of Reefing series. This week we are answering RMLLLLL's question from Week 34: “What do you guys think about testing for TDS in the RO water and changing the filters based on TDS only?" The quickest answer is that not all of the RO filter change intervals can be accurately determined solely by TDS. Filters like your sediment and carbon block pre-filters for example won't really affect TDS, and RO membranes have such an extended lifespan that continually monitoring them every time you make water is frankly a little overkill. The one exception to this rule however is DeIonization resin. Our DI resin is a mixed bed resin which means it contains cation and anion resins – each with their own distinct charge whether it be positive or negative. Contaminants that often show up as TDS are reduced as they bond to the surface of the resin. As the resin is depleted, the TDS will rise in tandem with a handy color change of the resin alerting you that it's time to replace the media. So follow along as we answer today's question, provide some helpful insight, and help make reefing just bit more fun and easy for you and your tank. *Legal Stuff* The purpose and content of this video is to provide general information regarding the products and their applications as presented in the video. Aquatic sales solutions, inc. And its officers, directors, employees and agents disclaim all express or implied warranties, in any way, related to the products and their application as presented in this video, make no representation or warranty regarding the products and the application as presented in this video and shall not be liable for any direct or indirect losses or damages of any type, including but not limited to punitive damages, or from personal injury or death resulting from or in any manner related to the video, and the products in and contents of the video. The viewer expressly agrees that aquatic sales solutions, inc. And its officers, directors, employees and agents shall not be liable for any damages or losses related to the products in and content of the video and hereby agrees to hold the foregoing harmless from any such losses or damages.