Brown algae making fake plants dull and dirty. Tank is clear as I do a weekly 15 gallons water change and gravel vac of my 55 gal corner tank. I have a aquatop canaster filter with us light and clean it maybe every 6 weeks with tank water. All inhabitants are doing fine. About 24 fish total fish most small approx 3" tetra varieties, Cory cats, and 2 goraminies. Have 3 African claw frog and everyone gets along fine.
I would use Hydrogen Peroxide rather than a Chlorine bleach to soak the ornaments. Hydrogen Peroxide converts to water in a short time - so a dechlorinator would not be necessary as I understand (but I am not a chemist). But I would still thoroughly rinse the ornaments and soak them in water for an hour or two.