Live phyto doesn't settle quickly, in my experience. I've left buckets of nanno, iso, and tetraselmis without agitation for a few days with minimal settling out at the bottom. Even nannochloropsis is like that, and that species isn't motile. I'm not sure why.How do you get the phyto to stay suspended with susch low/no flow?
Without flow I'd expect it to go to the bottom pretty fast.
It will eventually settle but I think that's when it starts to die off. The air is important for phyto primarily I think to provide sufficient CO2 for photosynthesis. I expect when phyto runs out of CO2 it will die. Maybe when used as a feed for copepods the pods provide enough co2 to prevent settling, or just the movement of the copepods is enough to keep things suspended. Or they just eat the phyto that settles out. I'm not sure.
Synnechococcus is a type of cyanobacteria alot of people have in their phyto cultures (often not known to them). Some may consider it a type of phyto, and pods will eat it. Synnechococcus does settle out faster than others, especially when very dense. Synnechococcus can get VERY dense, I've seen cyano cultures that look almost black there's so much of it.
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