Good morning everyone, my name is Frank and I join this site as I believe there is a first time for everything so please forgive any mistakes. I have had a pond for 12 years and at 62 I would like to take more time over it. I have a 1100 gall pond containing about 30 fish, 2 of which are Koi bred by accident. We have always suffered from green water and as our Hozelock Cyprio pressure uv box has broken we need to replace. Any help please as we believe Oase are the best bet. Also for cleaning we are impressed with the look of the Blagdon Pond Masta and the Oase equivalent. We would be very grateful for any help and advice and experiences if you would be kind enough to take the trouble ot respond. Thank you very much.