Today, I built a surface viewing box. This is my first attempt at building something that has to be water tight. I suppose it went OK...but I won't be building an aquarium or sump any time soon.
This box floats perfectly in any of the three openings on top of the tank and enables me to see better when I'm working up there. It also enables some top-down photography. Here are some samples.
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400 gal reef. Established April, 2007. 3 Sequence Dart, RM12-4 skimmer, 2 x OM4Ways, Yellow Tang, Maroon Clown (pair), Blonde Naso Tang, Vlamingi Tang, Foxface Rabbit, Unicorn Tang, 2 Pakistani Butterflies and a few coral gobies
My Tank:
http://www.canreef.com/vbulletin/showthread.php?t=28436