47-55.1 250 coolant sludge or hose lining breaking down?

[Hcb3200]

Could be a Iron Bacteria. Water wells get them here in the south especially if they get contaminated. This brown sludge looking stuff sticks to pipes and the rubber would be a good candidate for it to cling to. Bleach flush 1/4 per gallon is what is used on the wells. you dump it in your well. run the water in your pipes then let soak for 24 hours. over bleaching the mixture does not speed up the process I hear.
you could soak your hoses and see if that works.