The biological-based Re-Circulating Synthetic Sand Filter from E-Z Treat Company has passed NSF 350 Water Reuse, NSF 245 and NSF 40 testing. It was sampled for 34 weeks, including double stress tests instead of the normal 26 weeks with one stress test. Test results indicate BOD of 2, TSS of 1.9, turbidity of 2, DO of 3.5 and pH of 7.2. Systems are available from 100 to 100,000 gpd. 866/753-4770; www.eztreat.net.