Maytag MSE661FARS how do you adjust water hardness?

My friend has this dishwasher and has only recently started using salt in it as thought the all in one tabs were enough.

So we have filled the container to the top and I went back a month later and the salt container still seemed to be full.

Any idea where to adjust the water hardness on the machine or is it done automatically?

He cant find his manual.

Thanks.