We're renting an old house and are limited on many things. We do have city water, I am not sure if we have "hard water" (how do you know?) or if there's a water softener installed. The dishwasher is older; it gets things clean but will leave spots behind. I don't know if it they are hard water spots or something different. It's very noticeable when I put nonstick pots & pans in there, they require a wipe down with a sponge afterwards. Glasses are noticeable sometimes. Plastic things are also very noticeable.

I've tried two different dishwasher detergents. Cascade all in 1 complete, which is a packet of powder + a liquid; we've also used the Finish brand "powerball" tablets. Neither one is any better.

What is being left behind....detergent? Water stains?