T&T: re Holding Tank

[C. Marin Faure]

 >the best way to avoid problem to the macerator running dry, is to  
ditch the
POS impeller macerator and put a Sea Land pump...  they're a little more
money but will last forever and can run dry...  i've never gotten  
more than
2 or 3 years on a PAR or Jabsco POS, but my Sealand is now 8 years  
old and
going strong...


Pascal is correct in saying that a diaphragm pump like the Sealand is  
superior, at least in longevity, to the typical macerator pump.  But  
there are ways to extend the life of a macerator pump if it is  
impractical to install the larger diaphragm type.  When we replaced  
the plumbing to and from our aft holding tank I included a "T"  
fitting and a short vertical stub of PVC tubing just  ahead of the  
macerator pump.  It is blocked off with a PVC screw cap.  After the  
aft tank is empty I remove the cap pour two or three gallons of fresh  
water down the pipe and run it through the macerator pump and out the  
throughull.   I can't say for sure of course if this has helped  
prevent corrosion and buildup inside the pump chamber, but we've had  
the boat ten years and have had to change the aft macerator pump only  
once and that was due to a motor failure after some seven years, not  
an impeller failure.  We use the ubiquitous Jabsco macerator pumps,  
so there's nothing unique about the pump itself.


____________________
C. Marin Faure
GB36-403 "La Perouse"
Bellingham, Washington