Tom,

Good idea on adding a buffer tank before the sand filter.

I've seen the link you posted before. I like that system but it requires some pretty good height differences to keep it all gravity-fed.

For the biofilm, I've read it takes up to four weeks to start purifying the water. My plan is to have two sand fliters set up so that I can alternate cleaning them without losing the ability to purify water.

-Blast