You have an experienced dealer who will be glad to help you with any questions you may have. Please give him a call.
I talked to my dealer. The disk is a mineral sanitizing product that sits in the filter basket. It is blue and the brand is Sundance. They told me that it assists in keeping the water sanitized, but that I still needed to add chlorine to the water in order to get a reading for chlorine ppm on my test strips.
This led to a new problem. I added the chlorine and got quite a reaction. My water turned tea brown colored and I am in the process of emptying my tub. This time I'm going to make sure to add the metal defense as I fill the tub. Since my tub has had 3 water fills now, I think I'm going to use a new filter. The original filter is brown now too, just like the water.
The dealer told me that the factory filter would only last a month to begin with. Does anyone know if I just pick up a filter at the local hot tub stores out here in my neighborhood if that will work. Or does the filter need to be from ARctic Spas specifically? I'm guessing they are probably universal. Thanks!