Plankton cloud

[Arnold]

Its very curious the way the plankton form a cloud around the light also you can see the bigger organism like copepods and cyclops darting around the cloud I guess they feed on the microscopic fauna

sorry about the glass thats a kind of encrusting algae very difficult to get ride off in the back you can see also a healthy stem of Ruppia maritima growing very well

[Mustafa]

That cloud, and the fact that you have both algae and cyanobacteria everywhere, means that the tank has more than enough nutrients. They probably came with the substrate, added with the food, or some organic matter is decaying in there. I would not feed for several months at least.

[Arnold]

The tank its running since 4 months now, I only feed the shrimps once in all this time, a tiny pellet that the shrimps and snails eat in few hours. The plankton abundance I think its because I used "live" ocean water directly from the Atlantic and the tank its filled with microfauna. I have seen cyclops and ostracods feeding on the microscopic cloud of plankton

Cyclops


Ostracod

[Mustafa]

Yes, there may be microfauna in there, but nothing can thrive without nutrients. Nutrients have to come from somewhere. My best guess is, again, substrate (including rocks) has organic matter in it because it wasn't thoroughly washed, and/or decaying macroalgae/marimo balls or something similar organic in there. Bacteria need to feed on organic matter. They won't just bloom with nothing to eat.