AFM® performed the best in tests, more than twice as good as sand or any of the crushed glass products.
AFM® Grade 1 will remove more than 95% of all particles down to 4 microns.
Sand filters are often used prior to RO and UF membranes, when sand filters are operated properly, they will give excellent results. The filters also have the advantage that they are low cost and easy to maintain, however there is always room for improvement as new technology is developed.
Square Pharmaceuticals had an existing pretreatment to a Reverse Osmosis and UV system. The main problem was Pseudomonas bacteria growth in sand and carbon filters. Dryden Aqua provided an uprade that solved all problems and provided them significant performance benefits.