Posted By John Webster I have no direct practical experience of its use, however there are a number of advantages over conventional chlorination. From a H&S standpoint, the main one is the reduction in storage and handling of liquid or gaseous chlorine or of hypochlorite. There is, however, some evidence (sorry I do not have references) of a slight increase in risk to staff with respiratory ailments (eg asthma) if increased atmospheric ozone levels result. This is unlikely to affect bathers. The bather benefits fron reduced eye & mucosa irritation from the chloramines produced during chlorine treatment. Chloramined are also responsible for corrosion, particularly to supporting steelwork. Water quality wise, there are now strains of chlorine resistant pathogenic parasites such as Cryptosporidium parvum and bacteria like Legionella pneumophila which uv/ozone should deal with. Water chemistry is also easier to balance with fewer chemicals. It is even more important to ensure filtration systems are efficient with uv/ozone. The uv radiation will kill organisms, but these can be shielded by particulate matter in the water. Hope this helps John

Posted By John Webster Ken, New-ish to the UK, but in use for over 50 years in Europe, where there are several hundred thousand pools all using ozone. I understand that ozonation is now a requirement for all Olympic pools (Sydney was ozone, Atlanta was chlorine and had to be changed to ozone at a late stage following protests). John PS From your posting I had assumed you were to use full flow uv sterilisation followed by addition of ozone. Reading again, I suspect you may just be injecting ozone generated by uv light, in which case ignore my comments about filtration.