(Or, Why Didn't My DI cartridges Last as Long as You Estimated?) Is Carbon Dioxide Destroying the Capacity of Your DI Cartridges? Does Your DI Cartridge Not Last As Long As It Should? Silica and Phosphates in Your Water But the TDS is Zero? Then get SpectraPure's New CO2 Test Kit, (p.n. TK-CO2-01) Sale Price: $16.50 Call our Sales Line to order. 1-800-685-2783 CO2 – The Hidden Contaminate TDS meters cannot detect CO2, as it is an unseen contaminate only measured by chemical or pH tests. Its effect on downstream DI resin cartridges in RO/DI systems is two-fold; a decrease in the lifetime of the DI resin and a decrease in the purity of the DI water. High levels of CO2 from low-pH feed water can greatly decrease DI capacity and can result in DI water with high levels of silica and phosphates. SpectraPure’s simple CO2 Test Kit can easily and quickly measure this capacity-robbing contaminate. Not all water sources have high levels of CO2, but any CO2 in the water will reduce the capacity of the DI resins, so testing is essential to recognize the need for pretreatment to remove this hidden contaminate. Testing your feed water (tap water) is error-prone and often futile, as there are many elements in feed water that can affect the accuracy of the CO2 test results. Use the CO2 Test Kit to sample your RO water (pre-DI) and compare it to the post-DI reading. This is an excellent indicator of both CO2 presence and the capacity of the DI cartridge to remove it. CO2 in the post-DI water signifies the probable presence of silica and phosphates, as well. Q: If CO2 is an issue, what can I do about it? A: 1) Primarily, change your DI filters based on pass thru of CO2 with the test kit as you can determine DI exhaustion not shown by traditional TDS meters; the thinking being that if CO2 is detected passing thru your DI section, then silica and other difficult to remove compounds (not shown on TDS meters very well) are passing as well. 2) If you can justify the expense and maintenance, use a degassifier column to remove CO2, after the RO and before the DI. We don't sell the system itself, but you can get an idea from this: FAQ FOR REVERSE OSMOSIS That column would go in a barrel. the RO system would be controlled by the level in that barrel, and gravity or a pump would have to push the de-gassified RO water through the DI section. Scott SpectraPure, Inc.