Why is Cryptosporidium a problem for swimming pool operators?
Cryptosporidium is highly resistant to halogen (chlorine/bromine) disinfection. This is a concern in pools where the primary protection against disease transmission is halogen disinfection. Cryptosporidium oocysts, because they are microscopic, may pass through many types of pool sand filters and most cartridge filters. A diatomaceous earth filter can capture most of the oocysts. However, even with an effective filter it may take as long as 2 1/2 days to remove most of the oocysts from a pool (assuming a 6-hour turnover). More studies need to be undertaken before the effectiveness of nonhalogen liquid sanitizers and other methods of disinfection on Cryptosporidium are known. Additionally, new filter media and flocculents have not been studied to determine their effectiveness in removing Crypto oocysts. Once a pool is contaminated (for example, through a fecal accident or by rinsing a diaper in the pool), it can remain a source of infection for pool users for prolonged periods of time b
