ATO

[mike31154]

If you don't have room in the sump for a top off bottle and don't mind having a bottle sitting next to your stand (visible), you can do a variation of the gravity feed. Use an air pump on a timer to pressurize the container and have a feed line to mechanical float switch in your sump. Simple, nothing to burn out really, the air pump doesn't care if it runs a little longer than necessary. Just takes a little experimentation to dial in the timings. I run my air pump a few minutes every few hours and it keeps up nicely. Pretty unlikely to cause any major flooding, only electrical part is the air pump, nothing with wires in the water.