interactions between boiler flue and water catchment system

[lopezcalling]

I use a wood boiler as one heat input in a hydronic system. Another input for example are two evacuated tube solar arrays. They provide a lot of hot water, but I also burn a lot of wood, and store the Btus for space heating and domestic use. The wood is all dried not less than two years in a fully enclosed drying structure. I also catch all the rain water that falls on my roofs, and that has led to a real unpleasant discovery, that tiny bits of ejecta are coming out of the boiler flue. They look like tiny pieces of charcoal, but I would call it creosote or fly ash or some byproduct of combustion. It lands on my metal roof and finds its' way immediately into the downspouts and into my cistern. I have disconnected the 3 most impacted downspouts, and put pans under to look at the water and collect samples of debris and water. The water is amber colored. This can't be good. I'm making an arrangement with a sweep for monthly sweeping. Other than regular, probably weekly roof washing, does anybody have any ideas about this? Any ideas or links for water-soluble products of wood combustion I should be testing for and watching out for?