Overflow box not siphoning

[Johnny Reefer]

Originally Posted by TheReefGeek

You dont understand. It is not the whole sump volume, just the return section..... You could have a 100g sump, but a 5g return section.

Oh yes, I see. I didn't read the "drain section" part of your sentence.
Glad you agree with the drilled tank being better idea.

Cheers,

[TheReefGeek]

Yep, just for people who already run external overflows, there are some precautions that can and should be taken to minimize the risk: (some of these may apply to CPR style overflow, but I have no personal experience with them)

1. High flow through a u-tube to discourage air bubbles from accumulating in the top of the tube. Do not rely on a pump that can fail.
2. Ensure both ends of the u-tube are submerged even when the power goes out, so that siphon is maintained and flow will resume when power does
3. Observe daily, and clean as needed especially if algae forms in u-tube
4. Tank should be able to "absorb" return section of sump
5. Float switches to prevent pump run-dry is advised for all sump setups.
6. Float switch to cut return pump off when display level rises too high would be good as well.



I own my own diamond bits to drill with too.