Cambo,

I use only one filter in the jug and it is made out of a porous stone material that is copper in color and is cone shaped. I do put filters on my planes with cowlings and this is most of them. I have blown through the hose in the jug filters line in the opposite direction of fuel flow to see if it is clear by looking for small bubbles a couple times over the years to make sure it isn't getting clogged but have never experienced your situation. Maybe you got a bad gallon of fuel somewhere in the past and it is now just showing up. Factories make goof ups all the time.

Gibbs