That's not too bad, it could be the periphyton you are seeing. Periphyton is a matrix of nutrients, bacteria and algae that is the main filter for your pond.
Fish will feed off that layer, so don't feed your fish unless there's nothing left. (if you have fish)
If the algae is clogging your pump intake, that's an indication that the filtration setup isn't keeping up.
Depends on how often you are having to clean the intake.