Thanks for the responses! Watermom- you have been following this process of mine i think and answered so helpfully last time! So, given that Chlorine IS bleach - which is what i had suspected - is the quantity the man told me (6 litres a week) less then i would be advised to use of chlorine? In other words am i a bit less 'chemicalized' doing the litres of bleach thing as opposed to recommended chlorine strengths and doses? He was intimating that i would have a nearly chemical free pool!

And Gerri - I am no wiser as to what HDH 40 is then you! Something that kills algae though.....

Meanwhile - i'm off to read up on poolsolutions (the rest of my life has been on hold since getting this pool!)