You need to either add an ato or start adding ro/di water manually for evap. daily to keep water levels consistant. I bet you are having big salinity swings among other issues as a result.
I am. They fluctuate from week to week. I make 15 gallons of RO a week with a salinity of 1.026 and by the next week with the evap. My salinity is around 1.028
Are you topping off with ro mixed with salt? If so stop. You only need to add pure ro water for evap the salt does not evap with the water instead it accumulates and causes your sg to increase. Make sure you top off each day with only ro water.