Internal overflow design

[DEE’S reef]

So on facebook marketplace I found a 50 gallon acrylic tank that’s drilled with to hole on the back but I was wondering iff there’s a way to make a internal overflow so I can plumb from the bottom of the tank.

 

[KrisReef]

Yup, but I wouldn't do it myself because my acrylic skills are weak.

A simple hole through the bottom of the tank with a bulkhead adaptor and a standpipe can function fairly easily for this process. A screened intake fitting, and a proper sump to avoid over filling the tank if the screen gets cloughed is how many fish stores keep their tanks running without the typical external overflow.