I have a wash down nozzle that uses compressed air and coolant; it works on the venturi principle so you just have a tube goind down into the coolant tank. I think I bought it at an auto parts store, and it was intended for using a degreaser mix in hot water to clean engines. This works very well because the air gives the blast and the coolant the wash.
If you get something like this just remember to take the coolant pickup tube out of the tank when you finish. I didn't once and left the nozzle on the floor with the result I siphoned forty gallons of coolant out onto the floor overnight.
An open mind is a virtue...so long as all the common sense has not leaked out.