Algae help needed

[ReefMadness]

that may work but I would microscope those dinos to rule out some treatment methods. amphidinium are more common and considerably easier to deal with than the prorocentrum I fought for over a year.
otherwise, affordable jebao uv sterilizers can be found on eBay that only require a pump and rather than nutrient loading the system the better road to me is just to start the stability routine through an easily repeatable feeding regimen and perhaps a new fish or 2. instability may well have got this mess started and doesn't help remedy it.