EasyBee

I know this is what this form does not normally deal with, but I bought a house with a jetted whirlpool tub that has an insane amount of brown flaky biofilm coming out of it. We have tried using bathroom products and OxiClean, but no good. I have some CLR and some tsp but I'm afraid to use those products for fear of messing up the tub. Can someone please point me in the right direction to doing a major biofilm removal on the inside of these pipes that I can't reach it all?