My experience is limited to four deuces only. All others may be completely different, though I doubt it.
Each of the four has had a dirty fuel tank. Algae, perhaps rust also as they seem to go hand in hand, in possibly some quantity in the bottom. When I see algae, I see water also. That probably is where the rust forms in the tank.
When I changed the fuel filters, each and everyone had rust and goo in all of the filter cans. I cleaned it as well as I could, initially. But, the more I thought about it, more rust has to form over time and I began thinking about how to stop the rust because it has to be a problem over time. That is when the jatonka spin on primary came to mind. In a short time the first rust source in the filters was eliminated. Now, I worry about the secondary filter cans. They will rust again unless they are 1) replaced with new cans which will eventually rust also; 2) sand blasted and perhaps powder coated to retard the rust coming back or the secondary fuel filters get replaced with either spin on adapters or completely replaced with another kind of filter holder with spin on filters.
Looking at aftermarket filter set ups they appear mostly to be in the above $500 price range.
So, the decision is to either purchase one of the after market kits or find an alternative, it would appear.
It will do little good to clean the fuel tank if the filter cans produce rust also.