We back flushed the vent and then filled tank with fresh water and the vent is clear and overflowing fine and does not appear to be a clog. I can see quite a few have viewed my post but no comments. We welcome any and all advice as we are stumped.
More information, the most offensive spaces of the odor
on board are in a locker in the saloon
and under the sink in the bathroom. These are both connected via open air space under the floor so it is difficult to tell which is the source.
Here are some other things we were thinking about
1) We have a sea water cooled dc power fridge that has hoses in the saloon
locker with most offensive odor
. Could the odor be from dead critters in the hose? We think this is unlikely as the fridge runs every day and has a filter at the intake thru-hull.
2) Since the holding tank drain hose is under the sink and that is a place for the offensive smell, could we have a permeated hose and if so how can we tell? Note again the hose is 7 months old.