If this is the case we recommend the use of two tried and true aquascape products.
Green carpet algae.
Ecoblast granular in combination with powdered sab stream pond cleaner.
It is typically blue green in color but it can be greenish brown to black or even red in color.
A severe overgrowth of cyanobacteria can gather into a foamy scum at the surface of the water.
It is also called slime algae or smear algae which is an appropriate name as it is very slimy and often gives off an unpleasant swampy or fishy odor.
The mossy green slime can deteriorate an outdoor carpet if not removed properly.
Green carpet algae this is probably the most common type.
Wet and humid conditions can cause algae to spout and spread quickly in an outdoor carpet.
Fast spreading this thick green variant covers rocks glass and décor quickly.
It looks like small bristles in a blue green to black green and can be tough to eradicate if left to grow for too long.
If the algae is particularly bad you may begin referring to it as carpet algae as it is also commonly known particularly if it s beginning to take over or carpet your pond.