Sludge in drain hoses

Me again…..While I was doing my repair yesterday, I found black sludge in the ‘ripples’ of the drain hose from the tub to the pump. I assume that this is also in the drain hose running from the pump outwards. I normally do not use the electric heater in the washing machine…as my machine is old, I can use an ‘economy wash’, which uses the temperature of the water from the hot water cylinder. (As originally American, where none of our washing machines have the ability to heat the water, I found this ability quite unusual. Additionally, I see that the newer machines FORCE you to heat the water….there is no longer any choice for an economy wash. I find this appalling!!)
Anyway, I certainly wasn’t in the mood yesterday to start removing hoses and cleaning them out. When I dismantled the machine, I cleaned the plastic tub (it wasn’t dirty) and also cleaned the heater element (slightly greasy). I want to clean the hoses (easily). I found a recommendation for Affresh on your website. I’m on a septic tank, so have to be careful as to what I use (Affresh says it’s safe for septic tanks…??). Will this clean out the drain hoses? If not, what else would you suggest (other than just leaving them alone, which is probably an option. The machine is 40 years old, and frankly, there wasn’t THAT much sludge in the hose.)
Another question: that hose from the tub to the tank has a ‘reservoir’ apparently. Is this meant to catch the heavier particles that are being drained out? My machine has no filter (which I find strange…)
Thanks for any advice (as usual).