I understand. Would introducing live phytoplankton be helpful? I could potentially grow some of my own or also I could consider purchasing.
I read algaebarn has a big thing on their site about dinos and oceanmagic live plankton being beneficial.
However, i was told repeatedly not to add any aminos and algae barn says their ocean magik has a lot of aminos.
If you were dealing with amphidinium or prorocentrum I would really urge you to dose phyto and pods but with ostreopsis properly plumbed and sized UV is all that's needed other than restoring nutrient balance. The UV is the treatment for ostreopsis.