I was helping a friend with his pool and I noticed that his pipes inner side was all coated with soil (earth ).
He used well water and I think the well collapsed. One of the filter actually cracked due to clogging!!! Any how, now its city water being used. There is no way to clean the inner side of the pipes and I notice the brown soil coating, like any pool that got flooded by mud slide..something like that.

Will soil coating allow biofilm to grow and in return promote algae or bacteria ...or keep consuming chlorine ?
I knew my own pool plumbing has some thin coating from 2007 flood but nothing as thick or dark like my friend's pool plumbing.

Any advice on what to do ?

I saw on Discovery Chanel, they clean concrete delivery pipe for construction work with sponge ball and high pressure air. I can do that, but pool plumbing has so many "Tees" and valves...the sponge ball might get stuck somewhere...

Thanks in advance