How to Bring Down Salinity

The salinity in my 65 gal tank (about 2 months old now) runs consistently at 1.028. I'm losing about a gallon a day to evaporation and replace with fresh RO/DI water which brings it down to 1.026. By the end of the day, it's back up to 1.028 (I'm assuming because of evaporation).

I've been using a plastic hydrometer and getting the consistent high reading, so I thought it was very possible the hydrometer wasn't accurate. I bought a refractometer, calibrated it, and sure enough the salinity is running at 1.026 - 1.028.

I've been doing water changes with RODI that tests at 1.024 consistently, so I'm not adding water that has a high salinity...

Here's my question: How do I safely get the water down to 1.023 so that the "evaporate/salinity goes up" cycle stays in the safe range?

I'm afraid to lower the salinity too fast by doing a water change with a significantly lower salinity...does that make sense? In other words, I don't want to mix salt and fresh RODI water to produce (for argument) replacement water that is 1.020. I worry that it will be too drastic a change for livestock (mushroom corals, zoanthid corals, 4 fish, green hammer coral, cleaner shrimp & coco worm).

I'd love some advice...
Thanks,
Leigh