With my 115g total volume I go through 1-2g top off per day, dependent on the time of year.
My Tunze 3155 runs about once/hour pumping about 300/350mls each time
8 years on and it's still working fine
Yes, the default ATK programming lets it run once per hour if the water level is below the bottom optical sensor. Please read my ATK tutorial for a detailed overview of the programming and how it's designed to work: