A green film, as meadowlark has noted, is in and of itself nothing to worry about. If a Secchi disk in my pond disappeared at 14 inches, however, I would be very nervous, indeed, that a stretch of several cloudy days in a row might be the beginnings of disaster. I try to keep mine just under 18 inches, using the AAT (Auburn Arm Test).
You might want to consider using the finely granular, instantly dissolving fertilizer which is now widely available in the future. It is much easier to control how much phosphate is going into your pond and when. It is also good to remember that phosphate doesn�t go away until it is washed away.
Lou 13.5
