Looking for opinions 4 tank

LOL yea, my bad I had my cousins over for Easter and they were attacking me while I was reading. But I'm planning on doing a 20 gallon fuge, But I got one question, do you get over flows when your power goes out figuring that you have a smaller tank on the bottom? How is that preventable?

 

No overflows if designed correctly. The level of the overflow mechanism in the main tank will dictate when water will stop flowing out of it. Since water isn't being pumped from the wet/dry back to the main tank during a power outage, once the water level in the main tank descends beneath the overflow teeth, the siphon is interrupted, ready to come back when the power returns.

If done properly, the main tank will stop delivering water to the wet/dry before the water level in the wet/dry overflows.

It's much easier seen than explained. During normal operation, the water level in the sump or wet/dry, will be such that after accepting all water from the main tank; will still be below the confines of the wet/dry itself.

 

If the power goes out then the water drains into the sump from the fuge AND the display tank. To prevent an overflow, you simply need to make sure there is enough room in the sump to handle the extra load. What that means is you don't keep the sump full of water. If you look at the pic of my sump again you will see that it's not totally full.