The after WC on the left looks to be lighter than before WC and from tap.
probably the water conditioner because your right.. after WC is slightly lighter than out of tap .
The after WC on the left looks to be lighter than before WC and from tap.
At my old house I had the same problem, I used to put tap water into a old tank and turned it into a giant algea scrubber then pump it into the main tank on water change day then refill it for the week. Worked well with a noticeable drop in nitrates as long as you have the room.

I got a quick qoute on a whole house water softener and a r.o. for the kitchen. it was around 4 with install.
didn't think about a r.o. system for the house.. how much did you pay for your ,assuming you have one, if you don't mind me asking