Vicar8, welcome to the forum.

I also have an Aquarite SWG that's 8 years old and I'm on the original cell.

Based on my experience, the lower the amp draw, the lower the salt level. Since you indicated your unit is new, I would call the customer service number on the inside of your control box. 3.21 amps is very low for 3500 salt level and warm water. Some Ting Wong.

Also, the unit operates on 100 minute cycles and the output dial is a direct percentage run time. In other words, if your output dial is 60%, you will generate for 60 minutes, then rest for the next 40. When you dialed your output to 60 and showed no amp draw, your % run time for that cycle had elapsed and were resting. Hope this helps.