Taylor,
Here you go...
http://reefkeeping.com/issues/2003-01/gt/index.php
Having an external unit lets you remove it for cleaning/maintenance, and the odd photo shoot. Amano does similar things in his tanks. There's stuff in the tanks that aren't there in the photos. When done you just stick them back in. One "benefit" is no extra holes in the tank so in theory fewer potential leak issues. The big drawback is what happens if you keep pumping water into a tank with an external overflow that isn't working? Well, you get another kind of overflow which is not nearly so much fun.
-
S
Here you go...
http://reefkeeping.com/issues/2003-01/gt/index.php
Having an external unit lets you remove it for cleaning/maintenance, and the odd photo shoot. Amano does similar things in his tanks. There's stuff in the tanks that aren't there in the photos. When done you just stick them back in. One "benefit" is no extra holes in the tank so in theory fewer potential leak issues. The big drawback is what happens if you keep pumping water into a tank with an external overflow that isn't working? Well, you get another kind of overflow which is not nearly so much fun.
-
S