You can get a relatively inexpensive and semi-reliable automatic top off system, but with an Automatic Top Off (ATO) you have to worry about pumps, head pressure and the possibility of a siphon. The new AVAST Marine Works Deluxe ATO takes all of that out of the equation using a peristaltic pump to replace the water evaporated from your system. Sure this may be a bit pricier than simpler systems, but this one give you reliability and stability.
Using the peristaltic pump, the AVAST Deluxe ATO will give precise replentishment with little maintenance. Plus with 20 feet of head pressure, you can relocate your ATO reservoir to another part of the house, freeing up space under your tank and eliminating the need to carry jugs of water all over your house.
The peristaltic pump in this kit is powered by a 12v DC motor and can deliver up to 100ml in a minute. The system uses a pressure sensor tube to detect water levels. This, along with the delivery tube, are held in a magnet mount that will adhere to tanks up to 1/2 in. thick. These are currently on back order as many hobbyists grabbed them over the Black Friday sale and they run $189.99.