I think the article said that you could refeed some of the algae. But the main point was using it for export. While the growing algae keeps the DOCs locked up, you have to prune it to remove the DOCs permanently. Anything you recycle in the tank stays in the tank, but every time I throw out 5 pounds of algae, I am removing those nutrients from the water permanently.
You can remove DOC
Physical removal like protein skimming,
Chemical binding agents like GFO
or organic agents like algae and the live bacteria in rock.
Just how I do it...