Review on Ultimate Blue Gallon Membrane Filter: Pure Water at its Finest by Darian Massey

The 3rd stage filter in our Pure Blue h2o reverse osmosis system was about 2 1/2 years old. It was the original Stage 3 filter that came with our new system. This filter should last 2-5 years. As we understand it, actual lifespan depends on pH and water quality. We change the 1st and 2nd stage filters every 6 months and the 4th stage filters every year as recommended. Our tap water (Pure Blue H2o before reverse osmosis) shows 450 ppm with our TDS meter - very hard water. Up until a few months ago, the water from our Pure Blue H2o reverse osmosis system was typically 30-35 ppm. A few weeks ago it suddenly went up to 60-65 ppm. Installed a new 3rd stage filter and the ppm dropped to 20ppm after allowing 60-65ppm of water to leave the storage tank. A pretty significant drop. Without a TDS meter, we would never have known the 3rd stage filter needed replacing. If you are using a Pure Blue H2o reverse osmosis system, it is highly recommended that you purchase a TDS meter ($15-20 for Revain) to accurately pinpoint the best time to replace a stage. 3 filters.