Black Film on Vinyl Liner

[MikeD]

I opened my pool 2 weeks ago - the pool water appears clear and chlorine level is high - still trying to get the PH and Alkalinity levels up - over the last few days, a black film has built up along the pool walls and on portions of the pool floor. It doesn't brush off, but does clean off partially when scrubbed with bleach. Could the low PH and Alkalinity have caused this black film to build up?