Cusser
+1y
Yes, I do this yearly, the spa is nearly 24 years old now !!! We bought it new for $3000. Over the years I've had to learn to be my own spa repairman, that's for sure.
OK: the homebrew, as suggested by the sleazy salesguy Bob back in 1988 ("this aeration button will produce more action").
I mix in about 25% linseed oil (Home Depot or Ace) into original type mineral spirits base Thompson's Water Seal, the type that's flammable and has tons of flammability data on it. If you shake it and it's opaque and whitish, that's an emulsion, and the wrong stuff. I still have some of that original Water Seal left over, as I bought several gallons a few years ago. If I was out of that and couldn't get more, I'd just use linseed oil in mineral spirits. I just use an old paintbrush, and the beautiful can in the photo is about the volume I need.