Ted,

All the reasons you list are very valid.

I have found plenty of fish, shrimp, fry, snails, etc in my boxes. Thank goodness for those tiny nets..............with the plumbing in there, can be hard to catch em!

The big ones you didn't list (IMO) are surface skimming and constant adjustment of the intake. The overflows allows the water to skim off the top OVER A WIDER AREA and without adjustment to the intake. This keeps the surface scum down and facilitates air/water exchange, and looks better

If you just had a pipe stuck straight up, you would have to constantly adjust it or keep the same EXACT water level in the tank at all times. Good luck with that lol

The water collects in the overflows and eventually will be higher than the opening of the intake. The higher this is, the more water in the overflow box and less noise and degassing....

Ideally, (again IMO) the overflow would be thin and run along the ENTIRE back length of the tank. This would be less visible and offer excellent surface skimming if you are into that sort of thing lol


Hope this helps.