There is an article published in the August 15th issue of Service Industry News (catered to the swimming pool industry) that I would like to make public. Without quoting the entire article, there are 748,000 cases of cryptosporidium infections transmitted through swimming pools. It produces flu like symptoms that can last from 2 - 4 weeks and represents a real threat to recreational swimmers. It is highly resistant to traditional chlorine disinfection methods. Cryptosporidium can lurk in a pool for 7 days, almost totally unaffected by chlorine. The sickness is transmitted when swimmers ingest the water, an inadvertent but normal swimming act. The EPA has found that adult swimmers typically swallow 24 milliliters of water per swim period. Children consume twice that much. The cryptosporidium is a result of someone being in the pool with diarrhea. Parents should take their children to the bathroom often and diapers checked regularly. Washing before getting into the pool is a great idea. Of course, this is another good reason to have your own pool instead of going to community pools or waterparks. You can regulate swimmers much more if you know who they are. Since chlorination is not particularly efficient in treating it, there are a couple of new studies that have shown ultraviolet radiation is effective at inactivating bacteria, viruses and other pathogenic organisms. UV offers no residual protection as it is only effective when passing through the UV light. This means that if you suspect your pool has been exposed to someone with diarrhea, then you should run the pump and the UV ozone system 24 hrs a day for at least 7 days to kill it. Normal cartridge, D.E. or sand filters are efficient at handling the smaller cryptosporidium organisms.