I used Sonar earlier this year to kill off most of the weeds in my pond, it even reduced the FA.

However today I noticed several blooms of algae that didn't look like the typical green/light green FA.

Researching blue green algae is turning up lots of different images varying from a scum layer to mats of algae.

The current blooms are green with dark almost bubbling spots (like a bubble on a pizza).

Wondering if anyone has any idea, pics below.

Thanks

That is primarily bluegreen mat forming algae with a few green algae filaments mixed in that typically grows on bare mud bottoms of relatively new ponds. I often call it mud puddle algae. Older ponds with accumulated organic sediments usually do not get lots of this type of algae. When you killed all or most all the weeds with sonar this heavily reduced the amount of competition for space on the bottom. Bottom sediments are rich in nutrients and production of nutrients. Then the current bluegreen mats could flourish when there was minimal vegetation competition on the bottom. The new current problem will be harder to fix than the first weed problem because it is resistant to most herbicides/algacides.

Thanks for the reply.

Its a older pond, 25 years or so with heavy organic muck.

I did use a excavator this summer to muck out the first 15 feet from the shore right where the new algae is growing.

Its a 2+ acre pond and all the algae is in one spot, but that's also where the wind blows everything.

I also have 5 diffusers running 12 hrs every night.

Is this a toxic blue green algae?

I have dogs that love to play in the water but I have been keeping them away.

Looks like something I'd like to introduce into Bill Ds pond in appreciation for the Goldfish.

To be on the safe side, I wouldn't let the dogs be eating or licking the algae off their bodies. Swimmming in the pond would be okay in areas away from the mats of algae.