Like Reefguy already mentioned it usually is sufficient to clear the water once and let the UV run for a while. After the water is cleared and the conditions have stabilized the bloom won´t come back. I think it is because in a stabilized tank there are always enough filter feeders to keep phytoplankton in check.
The funny thing is that I introduced the Nannochloropsis bloom myself with a live phytoplankton product. I was a bit disappointed to see that much phytoplanton doesn´t help much. Even filter feeders didn´t like the bloom at all. Maybe it is too much of just one kind.
It's a matter of how much of the stuff can possibly be consumed.
I like lasagna a lot - but if you filled my house with it, most of that would rot before I could possibly eat it all - and if the lasagna was _breeding_, well . . . . (The fact that the density of the stuff cuts off light to photosynthetic organisms in the lower reaches doesn't help much either...)
Yes, of course, but I thought the sea squirts at least would be happy with the lots of fresh and growing Nannochloropsis ... like standing in a lasagna field or under a canelloni tree ...