Auto top off siphoning issue

[AnnaCassandra]

I recently purchased an auto top off because we are going out of town for a few days and enough water evaporates daily that the return pump in the sump would be sucking air before we made it back home.
I can't remember the brand off the top of my head but it's just a tube that connects to a power supply that turns a pump on when the water level drops because of reduced air pressure in the tube. The pump is just a marineland maxi-jet that I already had and I'm using a 5gal water jug (like the kind you take camping with the spout as a water reservoir) it works fine when the water level in the reservoir is close to the same as the sump but when the jug is full or close to empty the water siphons even when the pump is off.

I could just get a check valve but that will only stop the water from back siphoning into the jug when the reservoir is low, it won't stop the sump from overfilling when the jug is full. What do you do to keep it from siphoning?

 

[elFloyd]

Peristaltic pump... won't siphon.

http://https://www.avastmarine.com/products/peristaltic-pump-for-auto-top-off

 

[Smokey Stover]

The end of the hose that pumps water into the sump should be above the set water level in the sump, No siphon.

 

[elFloyd]

The end of the hose that pumps water into the sump should be above the set water level in the sump, No siphon.

That works too!