very interesting thread
i dont know if your tyalking about a different kind of uv clarafier(sp) but all the ones i have read about dont actually kill the algae they force it to clump together so it can be filtered out by a seperate filter
http://www.tlc-direct.co.uk/Main_Ind...s_1/index.html
this might mean you need a filter in your system too
Idris