Is it necessary to put salt in the salt dispenser, when using a 3-in-one tablet ( I also have 5-in-1) which includes salt. I live in a hard water area.
The salt in the tablet is to soften the water. The salt in the dispenser is to periodically flush out a water softening device built in.
If you don't flush out the device it will cease to function properly.
I live in a very hard water area and an engineer advised me to buy Finish Classic, not 3,4 or 5 in 1. Then use the salt dispenser and separate rinse aid.