Just my opinion...
The dangers presented by bacterial bloom are basically three:
(1) Bacteria increase oxygen demand, day & night (and increase CO2 content). That may harm not only animals but plants, too. They respire oxygen all day long, and while during photosynthesis they can rely on oxygen they produce, during night they are relegated to oxygen in the water column. If it's low, plants suffer, and may die off quickly. Because of it's rapid effect, low oxygen is far more deadly than lack of CO2 or nutrients.
(2) Once plants get troubled/damaged, they lack energy for defense against stressors, incl. facultative parasitic bacteria. The course of events may be disastrous.
(3) If the lack of oxygen gets serious, not only plants but bacteria themselves suffer. They die in large numbers and their dead cells contribute to the organic pollution. Beside that, they turn to anaerobic metabolism. That's always dangerous because anaerobic metabolism produces many unstable, only partially degraded organic compounds, many of which are outright poisonous to animals as well as plants.
Mind, I do not insist that these consequences must occur inevitably. Sometimes they do, other times not.
Be it me, I'd apply activated carbon, vigorous oxygenation, and multiple water changes. Never mind losing CO2. There's quite a lot of CO2 there due to bacterial respiration, and - as I've said - low CO2 does not kill. Low oxygen does.
