Thanks for all the responses. Bill,I don't have any floaters or anything to indicate that decay is an issue. Other than this occasional smell, which is gone again now, how do I know about a likely algae bloom in muddy water? My pond has yet to settle after six months, so I have no clue what's going on in the water. There's maybe 2 inches of visibility in some parts. I just checked the PH with an aquarium kit and it shows to be about 7.5 PH. Any further advice is appreciated - I have a post in the muddy water section titled "Clear as Mud" if anyone is so kind to surf over there. Thanks....