I'm looking for advice on what options I have to reduce the hardness in our hot tub.

After a fresh fill the hardness will be ~250 from the test strips.
After about 2 months the hardness gets upto 500-1000.
I maintain a steady ph of 7.2 and alk at ~80.

Ideas?

Maybe the CH is too high, you can add some scale defense to adjust the hardness of the water.

I think the water hardness is a concentration of the calcium and magnesium in your spa water. The ideal CH level for hot tubs and spas is 200-400 PPM, so if your level is below about 150 PPM, it isn't good there may some erosion on your spa equipment parts can occur...