[daniella3d]

My worries were more in case the main pipe would get clogged, lets say if a fish manage to get inside. I guess this is very unlikely anyway. In that case that the main pipe would be clogged inside, no emergency elbow would help. This is why the design with 2 overflow is a bit safer I tought.

Originally Posted by Reef Pilot

Yes, Mike, a T at the beginning of the slotted tube is even better and I would just put the cap back on the end. You really need only one emergency, as it is big enough to handle any flow that could go through the slots. I would just have a little screen cap or something over it to prevent fish from jumping in.

The beauty, too, of this design, is that the tank side plumbing does not need to be glued, and you can keep making adjustments to fit the tank until you are satisfied with the design.

When I was actually using this overflow as a refugium, I only had the slots (no emergency elbow) and macro algae, chaeto, caulerpa, etc, would collect there, but it never came close to plugging. The slots allow a lot of flow, and as the water rises, more slot area becomes available on the pipe. But I did keep an eye on it, and was planning to add that elbow on the end if necessary.