imho, "hardness" aka "mineral" tests are only a small part of the equation. Why not test it for everything. I see a lot of people buying water softeners without testing the water for all that ails it. Iron, ph, bacteria, other contaminants, flow rate etc are just a few issues. Water tests are cheap might as well know everything about it. You really should know your flow rate (GPM) to make sure the softener is properly sized. Do that by placing a 5 gal bucket at the lowest tap in the house and time how long it takes to fill. Divide minutes by 5 gallon to get flow rate. Make sure yu do this in front of the softener, not after or put your softener in bypass mode if there are no faucets/hose-bibs in front of the softener. Hopefully a basement laundry/utility sink or even an outdoor hose bib. Don't use a shower, kitchen or sink faucet as they are generally metered to be no more than 2.5 gpm. If you want to know if the system is softening, check hardness in front and behind the system.
I believe most people buy the wrong system or are sold the wrong system. Do the tests and have Ohio Pure Water (I trust them completely) specify a system or make sure your system is the right one. Assuming you're comfortable with plumbing, OPW ships the equipment to your door about 40%/50% cheaper than plumbing suppliers and will give you lifetime Q&A. And it's sized right and the rght equipment for your issues based on the water test. I've put in a few of their (Fleck) systems. They always help me when I need it (except weekends, holidays)
This is a good test kit, no lab fees.
This is the same kit sold by Ohio Pure Water but half the price at HD
Side note: If you aren't getting a salty taste in your water
and if the salt in the brine tank is dissolving and needing replacement, your control valve and brine valve are good. If salt is dissolving
and you're getting salty water, your control valve is bad. If salt isn't dissolving or the brine tank water is dingy, your brine valve is bad or the float valve isn't working or the discharge hose is kinked or clogged or the venturi jet is clogged or the filter screen is clogged. Not sure which system you have but they are easy fixes with Fleck equipment. Often times, only need cleaning.
The plastic beads in the tank also don't last forever. If everything is working correctly and still getting hard water, your system is sized incorrectly or the resin media beads in the resin tank are shot. The resin media beads don't last forever.