You can find uv sterilizers for less than $30 on ebay that will clear it up. They also have free shipping.
^Well the pond is only 150 Gallons. In 2 years, We've on;y cleaned the 5 gal Filter 3 times. We clean the prefilter in the pond once a week. It has always kept all the levels perfect. We have a very small backyard, so right now the filter works.
We have been using some Algae killing stuff that has been working great.
Hmmm....maybe. Would a simple pond clear liquid hurt the turtles, fish, or plants?