Mike Ondra <mondra@...>
As mentioned before, we experienced significant buildup of deposits
on the copper tube walls where the head pump hose feeds the holding
tank. Thickness on the main head was over 1/4" and the secondary
1/8". Removal took close to a hammer and chisel as the material was
quite hard and well bonded to the copper. Screw drivers of various
lengths and finally a stiff hacksaw blade physically removed most of
the deposits after great effort, bruised hands and ultimately aching
fingers, hands, and forearms. Next time it will be a 1 1/2" boring
Samples of the material were tested in jars of Drano, vinegar and
biological treatment for septic tanks. Only the vinegar seemed to
have an affect, softening the material to the point where it fell
apart when prodded with a screwdriver. The other samples remained
rock hard. So we proceeded with 10 hour straight vinegar treatement
from the head to the top of the inlet tube followed by flushing with
fresh water. Will inspect the results upon the next opportunity.
Several questions remain:
Cause - salt buildup from sea water flush? Do salts attach to
copper? Doesn't make sense as ships used to be clad with copper
sheeting, and copper is used extensively in bottom paints.
Can one assume that the exit tube to the through-hull is likewise
blocked? Future investigation. Perhaps this is why the through hull
valves are becoming increasingly stiff to operate.
Would weekly treatments with vinegar, as Gary suggests, be the
optimum solution to keep the pump, tubes and valve clean?
Do others have this problem? Especially is the problem specific to
applications with sea water flush AND copper tubing? Why is this
tube not plastic?
The through-hull and outlet copper pipe are bonded to the vessel
grounding system, but the inlet pipe that is giving us the problem
is not. Would doing so make a difference? Will know better after
examining the outlet pipe.
As we all know, optimally functioning heads are a blessing. Please
share your successes, or failures, on this issue.