I have been using SpaBalancer for about two months. A slimy layer has formed in the water at the edge of the spa. What is this and what can I do?

This is biofilm. Biofilm can show up all the time. If you have an older spa that has been treated with other sanitizers, you have biofilm in the plumbing. Biofilm is a colony of bacteria that is resistant to disinfectants. SpaBalancer slowly but surely dissolves this colony. This allows the biofilm to enter the spa room and settle on the walls. Sometimes this also happens with new whirlpools. This is due to the residual water in the pipes which comes from the factory filling for testing purposes. This phenomenon can also occur with very heavy loads.
In this case, we recommend shock treating the water with inorganic chlorine without stabilizer. This chlorine will have completely decomposed after one or two days. Do not use SpaBalancer again until the chlorine level is at 0 ppm. Otherwise, both agents would neutralize each other in their effect.