The water depot lol
They told me it will clog up my RO system in no time
As he sold you a water softener no doubt.
Our tap water comes out of a dugout on my property at pH 8+ with 350 - 500ppm depending on the season and I've bought all the gear to build my own custom RO filter. When I bought this place 20 years ago he had a softener hooked up using pot. chloride and the ppm from that was 300 higher than the water only filtered to 5µ. I'll be filtering down to 0.5µ before it gets to the RO membrane. That won't reduce the mineral content but will greatly reduce the left-over sediment after the 5µ and give me longer RO filter life. People on city water don't get much fine sediment and most RO units only filter to 5µ. My pressure isn't great and fluctuates when the pump kicks in and out so I'll never hit the 75gpd my filter is capable of but lower pressure only hurts the quantity and not the quality.
I do have some use for that softener I put on bypass shortly after moving in. The 150L brine tank will make a great reservoir for the corner of the grow room and I'll be piping it in using a float switch to keep it topped up. Got a little tap to put near the bottom.
RO filters are designed to make hard water pure and remove 99.9% of all mineral salts, lead etc and there is no reason to soften the water first. You're just replacing the mineral salts in your water with potassium chloride which is just another mineral salt for the RO filter to remove.
Listen to
@Troutguide and get your water analyzed to see what's in it and it may be fine to use on your plants tho I prefer RO for mine.