Seeing that Calcium build-up is just another readon why I tell boat owners to look at installing either a 3-way valve onto their thru hull seawater intake so the raw water can be closed off and the engine can then be run out of a 20 litre bucket of freshwster mixed with sum dishwashing liquid. Or a simple connection can be placed into the seawater strainer so a garden hose can be attatched to the strainer to flush the engine with. Saves time and a lot of money for a tiny outlay. Plus the added bonus of having the 3-way valve is that if God forbid the boat starts taking on water and the bilge pumps cant keep up or they fail you open the valve and with a suitable hose attatched you use the engine as a bilgepump. Plus I cant get over that the engines tube-stack has such a dead/unused portion in the middle.