Biological filtration?

[IslandGuy]

Have had my pond up for several months and recently added 3 comets. It is ~300 gallons. I have a skimmer which flows to a biological waterfall. The manufacturer is "Surepro". Inside the waterfall there is 2 blue "foam" filters and a bag of plastic balls. The balls are kind of "yucky" looking. Do you ever clean this filter? Or is this where the good bacteria grows?
I have been testing my water. Ammonia is just about non-existent, ph runs around 8.2 and kh is over 200. I have well water. The comets seem to be doing fine. I have noticed my water is not as clear as before. The pond is only 18" at its deepest spot. There is algae growing on the bottom of the pond and on the side of the rocks, skimmer, and also the waterfall. I am assuming this is all "normal"? I have 2 water lillies, a hawthorn, an 2 other plants I don't remember their name but they are in shallow water and grow straight up like stalks...I have the name somewhere.
So any feedback would be appreciated. I am just wondering if things sound "right"?

Thanks,
Jim

 

[DrCase]

Take a 5 gal bucket of pond water and flush out that filter, if it has a drain..
Dont use city water.

 

[kirscp]

Chlorine will kill the beneficial bacteria within your bio filter. As stated above, use pond water to flush the filter.

 

[IslandGuy]

Thanks, I did just that this morning. I have a small pump and just sprayed down the bio-balls with the water from the pond. Don't have to worry about chlorine as we are on well water that is chemically untreated.