AIO water level fluctuations with ATO

[dbleoh7]

I'm looking for a solution to a problem I have with my 10 gallon Waterbox AIO. I have both my ATO sensor and return hose in the return pump chamber (Chamber 3). Everything works very well until a large snail goes over the overflow and temporarily obstructs the overflow causing the ATO to go off and increase the water level in chamber 3 which subsequently increases the level in chambers 2, 1 and the display and then the system is all the same water level and the overflow is no longer really an overflow. Is there a solution to rearrange the setup I have to circumvent this or should I get rid of the larger snails and get smaller ones?

Chambers 1-3 left to right:

Chamber 1(overflow): Overflow from display tank into sump, filter sock
Chamber 2: mechanical/biological filtration
Chamber 3 (return): Heater, ATO sensor, ATO return hose and return pump back to display tank

 

[Copingwithpods]

Your set up is correct and I think should be left as is. If the snail is big enough to block that much of the over flow I would just get rid of it. How big is that guy?

 

[NeonRabbit221B]

Zip tie a piece of egg crate to the overflow in the display section. Should stop the snails from covering it completely.