How often do you make sure to top off your tank?

Since many of the tanks tend to slowly drain tanks to evaporation, how often do you make sure to keep your tank at any given level to avoid any issues with sanity levels being thrown off (or other levels building a tad too higher than one would like)? Do you have an automatic refill system that you use (ex; a sump that will keep the main display tank filled up at the correct levels while the sump may drain over time), or do you manually do it every single time?