How to make an ATO switch more sensitive?

Because I have a nano tank (5 gallons) the evaporation of water is less than the 90 gallon tank I used to have the ATO on that I'm using now for my 5 gallon. SO I was wondering is I can DIY a way to make my float switch more sensitive to water levels because my ATO only kicks on if the water level drops 3/4" which isn't ideal for my tank because I'm getting large salinity swings. I try to keep my salinity at 1.025 but when my float switch is gets down to where it's going to kick on my salinity goes up to 1.028 and then the switch goes kicks on it drops down to 1.025 instantly and my SPS is not happy about it. Niether are my fish as when the ATO kicks on the scramble to go hide and get a little stressed for 20 minutes or so. So I need a way to DIY my float switch to be more sensitive, like 1/4" of water level drop sensitive. Any ideas?



By the way I have a JBJ ATO.