Originally Posted by Ziggy953
Any overflow box that has to pull water up and over the edge of a tank can fail. I personally trust only drilled. There is no way for them to fail.
Now the CPR style overflow has a better reputation then the ones that use the "U" Tube. Either way they can fail.
I am not trying to be argumentitive, only to understand...
I have always heard that the CPR style ("S") are at greater risk, and require a small pump to function. Unfortunately I do not have those sources in front of me and so cannot quote them.
As I look at my drilled tank I see a tube that is the same shape as the "U" type overflow. Here is my understanding of how each works: In both cases, the tank level rises as the return pump delivers water to the tank. At a certain level, water flows through the plastic "teeth"(?), either into the box or into the built-in overflow area. Both the overflow and the drilled tank deliver water to the sump via a u-shaped tube that rises above the water level and then below it again.
So I do not see the difference. Again, I'm not saying you're wrong, I'm just asking if you can help me understand at what point (specifically) the overflow might fail while the drilled version would not.
I would like to be able to explain this to others and supply full resoning.
Thanks in advance for your help.