Despite the fact that I am a rather new guy to out door ponds, I seem to have found the right balance in my 365 gallon pond. I have a home made filter sytem that so far works quite well. I only have to change and wash the filter once a week. I also installed a UV clearifier rated up to 1500 gallons. Three different types of potted lillies. I have one pink lilliy plant about six years old, and the two other are newly potted last month. On the shallow shelves I have several horse tail rush, one cat tail, and one cork screw something or another (that is growing well and fast).
I have seven Shubunkin's, three that are about five years old and the rest have been introduced to my pond this spring.
A month ago I introduced twenty five trap door live bearing snails that I believe to be the an extreme end to the overall algee problem that I had a month ago. Like Dr. Dave said, early spring is when we will have most of the string algee. With all of the living criters and plants in my pond, (at this point), my string algee is down to a minimum, the water is clystal clear and the fish seem to healthier than when I had them in a sixty gallon tub for a couple of years.