If this is the case we recommend the use of two tried and true aquascape products.
Green carpet algae.
Thanks for the imfo algae is green not black so maybe its not brush algae did find out one thing fish snails wont eat brush carpet algae found some real siamese algae eaters and they are stripping the leaves of the algae must just have the same growth pattern again thanks for the imfo.
Green carpet algae this is probably the most common type.
Ecoblast granular in combination with powdered sab stream pond cleaner.
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.
The mossy green slime can deteriorate an outdoor carpet if not removed properly.
Outdoor carpet adds a decorative element to cement porches and patios but the flooring is also affected by weather which could result in algae formation.
Wet and humid conditions can cause algae to spout and spread quickly in an outdoor carpet.
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.
It is typically blue green in color but it can be greenish brown to black or even red in color.
Beard algae this is the toughest type and therefore can be the hardest to remove.