Originally Posted by beefandpork
... Are these hard to install I am looking to stick it in the tank as I am using on 20 gallon tank with hang on back filter.
Just my opinion of course... but with a 20g tank I really can't see the need for an auto top off. With that small of a tank, you're probably only looking at 2-3 cups a day, at most. Unless you're away for long periods of time, that seems easy to deal with on a daily basis. Otherwise, you're looking at installing a bunch of float switches in a rather small area - those ATO setups are usually designed to be installed in a sump where you don't really care about room or how it looks.