Totally opaque meaning you can't see the bottom of the pond, but you can still see through a jar of pond water, right?
Sounds like suspended algae. Removing the attached algae will have benefited suspended algae by removing competition for nutrients, but your water may have turned green anyway. Do you have any plants in the pond? Barley extract and filtering through quilt batting are good quick fixes for suspended algae. You could use algaecide, of course, but I wouldn't.
How old is your pond, and if it's a different question, how long have you been taking care of it?