Hi All,
I'm a newbie to the forum and I'm trying to sort thru the types of "pond scum" to identify what I have and how to get rid of it. I'm attaching pictures in hope of identifying what I have in my pond and what to do about it.



Some details - I've lived beside this pond for 22 years and this scum issue has never happened before and there haven't been any changes in the area or how the pond is treated. It's a retention pond in between two condo buildings in a suburban setting. The pond drains into the village sewer system when it gets to a certain level and has always had an aerator running 24/7 from March through October (Chicago area). This year at the end of August this scum appeared and it hasn't gone away yet. The pond is serviced by a company and receives some treatment to deal with algae. I'm not sure what is used...I am working on finding that out.

Any ideas on what is happening and how to fix it? Any help is appreciated!

Hi Emma,

Welcome to PBF! I am not a pro but I have seen similar on my pond this summer. It showed up a couple days after we had had a lot of rain that added a good bit of runoff to the pond. I bottom aerate which I think might have actually exasperated the problem in my pond. It went away in 3 or 4 days. I assumed it was a combination of DOC (dissolved organic compounds) and other light material that washed in as it did not appear to me to be any type of algae. Hopefully, a pro will be along to provide a more helpful input.

Again, welcome!

Bill D.

Never seen that

Merely my opinions as I am not educated on the topics, but...

1.) Pollutants of some sort that may have been channeled to the catch basin by the street gutters and storm sewers.

2.) High levels of proteins (biological waste or man-made nutrients like soaps, food process waste, etc.

3.) Grey water...like from someone's washing machine or from a carwash.

It looks pretty nasty. Does it have a smell? Did the discoloration in the gravel come with it or has the gravel always been stained that oily color?

My first thought too was proteins too. Looks so much like your aeration is acting like a huge protein skimmer.