Woke up (at 4 AM) to water on the floor

You should really look into reducing the size of you return section or intentionally keeping it lower aslong as ur using hob overflows. Snails will find a way! If properly engineered the return should suck air when the DT is about to spill. If you have an ATO this is simple, with manual top ups it may be a bit annoying since you will be topping up more often but its better than a soggy floor!

 

I'll say it,
This does not make any sense!

1. A return can't suck air when the pump is running.
2. When using a HOB overflow, the height of the water in the DT doesn't change - unless you're on the brink of a flood in the next few seconds\mins.
3. To engineer a return to have such a fine balance between keeping the DT water at the correct height and not "sucking air" is a bad idea of a band-aid to a problem that needs to be corrected, not covered up. For strike two, this is completely impractical in a system where preventative measures and redundency are needed.
4. Please explain how you could have an ATO on a system like this? If you put it in either the DT or Sump, it would completely destroy the fine balance you're trying to achieve when the water level drops.



...FAIL

 

Really sorry to OP.

1. A return pump will suck air when the return section is empty. If you turn a pump on out of water...its sucking air.

2.correct! Never questioned this.

3.on my 55g its about 2.5 gallons. If the return section is full to my intentionally set limit and my overflow clogs the entire return section can be pumped into the dt without spilling over the edges unless my MP40 is on high...

4. You need 2 switches and its risky unless you use an aqualifter or other really slow pump. Iv only ever diy'd ato so im not sure about comercial units.

Heres a pic of my sump. I have markings on if from testing my water levels.if i fill the return between flood and fail and my overflow gets clogged i get wet carpet. If i keep it between hi and low neither a power outage or clogged overflow will spill anything.

Im sorry i offended you and you felt the need to call me on it but i'm only explaining my experiences. I'm not sure what the "FAIL" for.