I have very well established tank. It was running without a problem for a year.
As you can see it's heavy planted. Livestock : betta, some RCS shrimps which are breeding like crazy and two snails.
Food and soil are providing all necessary nutrients for plants - I don't use fertilizer at all. There is only small passive co2 diffuser. With high level of plants in tank and emersed air monstera roots, small palm there is literally no NO3 and I don't need to change water for weeks to keep my betta happy. I occasionally add evaporated water only.
Everything worked great, but recently I noticed Cyanobacteria on roots of my floating plants. Water Spangles and Duckweed are covering majority of surface, but some are glued with green algae.
Smelly green goo must be Cyanobacteria, however I might double check it and see it under a microscope.
The question is: why out of blue it appears there if nothing changed in the tank?