Hi, my pond has been established for about 4 years now. I have been having the following problems: Shortly after fish started feeding again I cleaned out the pump & filters & did a partial water change, for about a month the water was crystal clear & all tests on the water were fine, a week later I noticed the beginnings of a bout of blanket weed, I have had several previous problems with blanket weed before & have always been able to bring it under control with great success using Clover leaf treatment & later with Cloverleaf sludge buster. I treated pond as usual with Cloverleaf Blanket Control but unusually after several days the water was still quite milky coloured so I decided to do a water change again which I did & within a day or two the water was pretty good and clearing, about three days later it was starting to look very 'murky' again, during the last water change I did introduce some water lilies so this time I cleaned the pump out again & the filter & changed about 90% of the water, everything was fine & the water was very clear & all tests were good, about 12 hours later the water clarity was starting to deteriate again, I was gutted to say the least, the next day there was an improvement & the water appears to be getting clearer albeit quite slowly. Ever since I started the pond I have never had problems that I have not been able to solve with ease. Can anyone throw some light on the events that I have encountered, Many thanks, John (stingray).