Needing help with my salt levels - keeps going up

[Rodney]

2-5 gallons is a hefty top off , it wouldn't be surprising to see that size of an increase with a tank that size my tank is 125g with a 90g sump the top of is about a gallon every 10-12 hours on a DIY auto
Also how long is your water change water sitting before you do it, I found if I check it when I mix its lower than 12-24hrs later when I use it