cyber,
I read that there was a company that was building these for awhile and was also trying to sell algae with them also at an additional cost because it was to be a better algae, I will let you figure that one out.
I did run across these two:
Q: What type of algae is best to grow?
A: You don't have much choice; algae will grow based on lighting, flow and nutrients, and will even change as your nitrates and phosphates drop. All algae consume nitrate and phosphate, so it really doesn't matter what type algae it is. What matters is how MUCH grows.
Q: How often do you clean it?
A: Once a week (7 days), no matter what. This is probably the biggest hassle with scrubbers, and when it is not followed, it's THE biggest reason why a scrubber is not working as good as it should. When the algae gets too thick on the screen, it blocks the light from getting to the bottom layers. Thus the bottom layers die, and they put nitrate and phosphate and cloudiness into the water. Weekly cleaning eliminates this. If your screen is smaller than it should be, or if your nutrients are very high in your tank, your screen might fill up and need cleaning in just a few days. This is ESPECIALLY true if the screen is growing dark, oil-like algae. This type of algae will never get thick because it blocks out all the light, so it must be cleaned as soon as it grows. After the nutrients in your water come down, the dark algae will grow less, and the green algae will grow more (dark algae is caused by very high nutrients.)