How to snail-proof the float switch

[fishkeepersaltnfresh]

So, this morning I found water all over the floor. Initially, I thought that my tank had leaked. But then found out that the water was overflowing because of the top-off system. Thought that the float switch was broken.

But on closer inspection, I found out that the float switch was caught in "ON" position because 2 snails were resting on it.

How do I snail-proof my float switch? I hope my corals don't react very badly to this dip in salinity. I am going to try to make up for the salinity over the course of this week. 

[seabass]

You can make one out of PVC fittings or even a pill bottle.

   

There needs to be holes to allow the water to flow through the snail guard, but prevent snails from getting in.

 

You should really have a backup which cuts off your pump if the level goes higher than your first switch.  Often it's a different technology like optical or pressure, but even another float switch will provide some protection/redundancy.