Questions about building overflows and drilling a tank?

[Palster]

Originally Posted by Fudge

If durso is 1.5" and feedline is 1" and you leave a decent space between holes for flanges and the walls of the overflow for flange space you need about 8" minimum inside overflow dimensions.

Thanks everyone for your input. So when you say you need a minimum of 8" inside overflow dimensions is that total spill over length or do you mean the overflow has to be 8" by 8". Also are you saying that one overflow of this size would be able to handle the flow for this tank. I was thinking of using eggcrate at the top of the overflow (this is how it is done on my 90gal).

It looks as though there are a fair number of people running external overflows. It certainly would be easier than having to drill the tank. Aside from having to move the tank further from the wall I can see some advantages. I did read an article on one website where the author was claiming that when the power goes out and comes back on if the siphon for the external overflow fails to start back up when the return pump comes back on then you can have a flood.

Glenn