When I installed a new holding tank, I installed a 1.5 " vent as per
Peggy's wisdom at that time. Never had a problem with odors
since.

Doug
s/v Callista

"Hal Landen" wrote in message
...
I'm planning to install a new holding tank system in my 1959 Pearson
Triton Yawl. According to Peggy Hall in "Get Rid Of Boat Odors" it is
recommended that the vent in a holding tank be 1". But the standard
for 20 gallon tanks seems to be 5/8". It is better to cut a new 1"
vent outlet or live with the exisiting 5/8" vent?

Thanks,

Hal Landen