Anyone tried to build a filter like this?

[ponokareefer]

How is this method so much different than growing chaeto in a refugium? In both cases, you are setting up ideal situations for the algae to grow, so that it uses up the phosphate/nitrate in your system, thereby reducing the chance that algae won't grow in your main system. After you get too much chaeto, you can give it to someone else to start up their refugium, or throw the excess away. In the algae turf scrubber method, you have to scrape the excess algae away.