Evaporation Compensation

I am currently experiencing about five gallons of evaporation every week. This evaporation causes two problems:

1. It increases the salinity of the remaining water, and
2. Enough evaporation will drop the water-level in sump far enough that the return-pump can't push any water back up and the loop will be broken.

To help take care of these problems, I am using the auto top-off system from my old tank.

This float switch sits in the sump and monitors the water level. When the water gets too low, it activates a Maxijet 1200 (rated for 295 gallons-per-hour) that pumps in freshwater from a nearby reservoir.

Above the float switch is a backup switch that kills the pump if the water level reaches it.

Here is the freshwater reservoir that I am using. It holds 18 gallons and I fill it to the 12 gallon mark every two weeks.

I cut out a small hole in the lid so that I could close the container without kinking the pump tubing (which would restrict waterflow).