RG wrote:

Peggie:

I've got a SeaLand Tankwatch 4 monitor system for my holding tank. Lately,
the sending unit for the 1/2 full reading has become unreliable....

It's not any chemical buildup--you haven't used any chemicals. The
sender(s) are coated/clogged with the animal fats that are present in
waste. Detergent is the right cure, but it'll take a strong
detergent/water solution, not just a small bottle of it...and while it's
only the 1/2 sender that's malfunctioning now, the 3/4 and FULL are sure
to be next...so you'll need to fill the tank to do the whole job. I'd
use 2 gallons in a 40 gal. tank. Take the boat out and do what it takes
to agitate the solution for an hour or more...then let the solution sit
in the tank for a few days. If anything short of removing the sending
unit to clean 'em manually is gonna work at all, that's the only that
will. And it may not.

So my suggestion: bite the bullet and do what it takes to gain access to
the tank one last time and replace the guage with this one:
http://www.ferriellosales.com/ The sender--unless your tank is
metal--goes on the outside of the tank, so it can never get clogged.

A little background on this company..it's new. Dennis Ferriello was the
national sales manager for Snake River Electronics for a number of
years...he and Snake River came to a parting of ways recently...Dennis
started his own competing company. He also took both the Snake River
engineers with him. Their website is a bit "woofy" (painfully obviously
homemade)...but don't be put off by that...he's put his $$ into
designing and making tank level monitors that are far superior to Snake
River's instead of paying for glitzy web design. And it's paying
off...he's already captured a major segment of the OEM market, and word
of mouth is already creating a growning market among boat owners. I've
known Dennis for about 10 years. He's always been committed to quality,
and I'm glad to recommend his products.



--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://shop.sailboatowners.com/books...ku=90&cat=1304