So how it works is, you grow the bloom in a massive pond. Wait for it to fully fill up, skim half the pond, add more nutrients and then agitate. With the algae you skimmed off you dry it out then compress it into a brick and burry it. In a 100K years we can the burn it for coal power again. And then repeat that until you've grown enough biomass to match the amount of Carbon put in the atmosphere since the industrial revolution.

Does this expend less carbon than you captured? Skimming, gathering, transport, drying, compression, burying. I assume to reach "gigatons captured per year" this would require heavy machinery and industrial buildout. Not that its impossible, I'm just not sure its a net-negative in CO2.