Selection chart

[SantaMonica]

7766

http://algaescrubber.net/WhichOne.jpg

[SantaMonica]

8132

This guideline covers sizing:
http://www.santa-monica.cc/Which-one_p_63.html

And these videos cover usage, placement, etc:
https://www.youtube.com/user/SantaMonicaMale/playlists