Pulling my hair out! Aquarite 900

[JamesW]

I took the filter out and there was a uniform light brown coating that was not dirt!

Maybe iron.

 

[Bob Jakob]

Usually when chlorine levels can not be maintained by the cell there is an algae bloom around the corner! FC levels can never be allowed to dip below .5 ppm otherwise algae will be in your future! You probably need to SLAM!

 

[Pauls234]

For what it's worth, halfway through reading your initial post I thought more than likely low level algae.