We have an older hot tub that has been sitting empty for at least 2 years - I say empty, but it had some water in the seats that wasn't removed at some point in time. We are working to fix the leaks, rebuild the cabinet (needs new top boards), replace the foam insulation in the cabinet and remove the scale. We never properly balanced the water - I know better now, but was going off the poor advice of the previous owner.
I am doing well on all parts but the scale - I assume it is scale. It is white, rough and hard. Wiping with a towel or a Magic Eraser does nothing but tear up the eraser. I am assuming I will have to acid wash it. Can someone point me to some instructions for doing this safely? Currently the power pack is not hooked up, so water and anything else that I am using to clean the tub with is running out the bottom. From what I can tell, the hot tub has a "maintenance free acrylic finish" and hold 425 gallons.