[suiller]

E VISTO CHE SI SIAMO IN MERITO AI CIANOBATTERI...

Blue-Green Algae: This is actually Cyanobacteria. Commonly referred to by the initials BGA. BGA is a green shiny slimey algae. It's got a nasty smell to it. It tends to grow in sheets. It is very different from most algaes. BGA is a bizarre combination of bacteria and algae.
It is common in two different circumstances:

In very low nitrate situations (NUOVAMENTE NO3 BASSI...), BGA will sometimes form. It is able to get nitrogen from the air. I've seen BGA several times right near the surface, under the filter return. In this location, it can obtain nitrogen from the air. Adding Nitrate to maintain a 5-10ppm nitrate level often eliminates the BGA.

BGA has also been found to occur in situations where poor water currents (PORTATA DELLA POMPA RIDOTTA OPPURE OSTRUZIONE DEL FILTRO) in the tank result in low O2 levels in portions of the tank. In these cases, increasing water movement will often eliminate the BGA.
No fish will eat BGA. As stated above, BGA is a bacteria. Some studies suggest that BGA contains toxins. This would explain why nothing will eat it. As a last resort, antibiotics have been used to clear BGA. But antibiotics should be used carefully. They can damage bio-filter bacteria, and mis-use of antibiotics can be harmfull to the fish (SU QUESTO MI TROVO PIENAMENTE D'ACCORDO).