Cryptosporidium is a parasite that can cause serious health problems such as Diarrhoea, Nausea, Vomiting, Abdominal Cramps and Fever. If the affected person has a weakened immune system the infection is more severe and may be fatal.

The usual cause of contamination is by a loose (liquid) bowel movement into the pool water. C.Parvum oocysts are best treated by a combination of chemical treatment (inactivation) and filtration (removal).

The effectiveness of removal by filtration will depend on the efficiency of the filtration system (filter media/ filter bed depth, condition/ filtration rate etc.). Coagulation will assist in optimizing the filtration of Oocysts.

The efficiency of chlorine by itself is subject to debate around the world. The use of additional systems such as U.V and Ozone may greatly enhance the results.

Health Guidelines recommend Super Chlorination as a means if inactivation.         A CT value (Free chlorine (mg/L) x Time (minutes) ) of at least 15300 must be achieved in order to inactivate 99.9% of Oocysts. This equates to a Free Chlorine reading of 20mg/l for 12.75 hours or 10mg/L for 25.5 hours. (e.g. 12.75 x 20 x (60 minutes) = 15300. Following this chemical treatment and prior to re-opening the pool all filters should be backwashed to remove Oocysts and then the Chlorine residual should be reduced to normal levels by the addition of Sodium Thiosulphate.

An alternative method that is also recommended by Health Departments around the world is the use of Chlorine Dioxide. This may be used as both a preventative and an in-activator of existing Oocysts. It is generally accepted that a CT value of just 78 (using Chlorine Dioxide) will result in the inactivation of 99.9% of Oocysts. C-5 is a Chlorine Dioxide precursor which when activated will form Chlorine Dioxide in the pool water.

In the case of a suspected outbreak of Cryptosporidium we recommend a Chlorine Dioxide level of 1ppm be maintained for a period of at least 2.6 hours (CT 1 x 2.6 x 60 (minutes) = 156, Normal chlorination levels (1-3ppm) should be maintained . At the end of this period all filters should be backwashed to remove Oocysts.

NOTE: NO neutralization of Chlorine / Chlorine Dioxide is necessary. During treatment, it is important that all probes are isolated.