Im sure it can be done but maybe not worth all the PT. Will look into it, but would one not need a salt mixer as well for top up if so then space for becomes a problem for me.
Please don't make the mistake I made. Top-up must be RO only. Water changes need salt.
When I started I wonder why my SG kept increasing week to week, Till Viper/Kanga kindly informed me that when the water evaporates the salt is left behind


Now sitting back and enjoying a cold one.