[Subsea]

Twin,
I feel that my mud cryptic refugium is semi-cryptic because the whole back of stand is open to air flow and ambient light.

I have also included a 3G chaeto refugium in display tank overflow box. I figure the production of DOC and micro algae, a type of phytoplankton.

“Marine phytoplankton are mainly composed of micro algae known as dinoflagellates and diatoms, though other algae and cynobacteria can be present”.