Good idea Rick_D to backflush. In fact I backflushed with warm water aftwards. That seems to clean sticky messes better than cold water. And I use 5 drops of bleach in 2 qts of water also for cleaning. I let the pump and tubing soak in my 2qt bleach solution for a few minutes. I then backflush about 1 cup of that bleach solution with a slow, slow pump stroke.

“Well, I'm also interested in how *long* the filter will pull organics like coke out before the carbon
is tapped out and the filter would need to be replaced.”

That is a good question. In fact, for this test, I used an old cartridge. What do I consider old? When my pump stroke becomes twice as hard as normal. I want easy strokes when I’m out backpacking. I save these ‘old’ cartridges because they can still be used for gravity filtering in times of emergency. And I can do experiments like this <img src="/forums/images/graemlins/smile.gif" alt="" />