all above advice is excellent but if it doesnt work it could be algae in tank, easily solved by putting in algaecide and waiting. probably have to change filters too. black dot s in primary (small) filter.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.