Fish Disease

Question
I have been keeping marine aquarium for 10 years and during that time the aquarium has always been infected with velvet diseases.  I tried everything except avoid using natural sea water.

I am pretty sure now that this is the main cause because i was just collecting water from sea and let it mature in the aquarium. Living in Mauritius and just 10 metres from the sea make it easy for me to collect the water and also because no artificial salt mix is available in Mauritius, I need your advise about how to cure and use the natural salt water safely and free of anu disease.


Answer
if your not already, get a UV filter, this should help alot. if over the past 10 years you have been unable to get this disease out of your tank, is it possible to cook your live rock and start again? failing that i would just add the NSW straight to your tank, forget the maturing process.

i think your in a very fortunate possition to be able to use NSW in your tank, i wish the water over here in the uk was clean enough to do that