I have my vent like Francois's but mine doesn't dip down and it runs up to a fitting in the hull just below the rub rail. When I bought the boat the vent stanchion had been leaking for years so I eliminated it.
I still get terrible odors if we let any waste stay in there more than a week so I don't think just getting the dip out of your vent line is going to help.
I thought I read in Peggy's book you wanted 2 vents to create a cross breeze so the anerobic odors couldn't form. I may have been mistaken.
When I replaced my tank a couple of years ago, I had 2 openings installed in the top. Bought a Ronco tank.
I couldn't find a place to route a 2nd vent so I added a fish tank bubbler with a 1/4" hose through a hole in the capped fitting on the 2nd vent. hole. Thinking if I was pumping air in, it would pressurize the tank and keep the anerobic odors out. Hasn't worked that way. I had dropped the 1/4" hose to the bottom of the tank. I'm wondering now if I'm bubbling up the odors from the water/waste. I might cut the hose short so it's only sticks into the tank 2-3" and fills the air space above the water/waste with fresh air.
One thing when you order the Ronco tank, any fitting you put in the top of the tank, put it towards the stern side of the tank. I have one of my vent holes almost in the center of the tank and it hits the wood panel covering the tank. Their seems to be more height towards the stern side of the tank.
I still get terrible odors if we let any waste stay in there more than a week so I don't think just getting the dip out of your vent line is going to help.
I thought I read in Peggy's book you wanted 2 vents to create a cross breeze so the anerobic odors couldn't form. I may have been mistaken.
When I replaced my tank a couple of years ago, I had 2 openings installed in the top. Bought a Ronco tank.
I couldn't find a place to route a 2nd vent so I added a fish tank bubbler with a 1/4" hose through a hole in the capped fitting on the 2nd vent. hole. Thinking if I was pumping air in, it would pressurize the tank and keep the anerobic odors out. Hasn't worked that way. I had dropped the 1/4" hose to the bottom of the tank. I'm wondering now if I'm bubbling up the odors from the water/waste. I might cut the hose short so it's only sticks into the tank 2-3" and fills the air space above the water/waste with fresh air.
One thing when you order the Ronco tank, any fitting you put in the top of the tank, put it towards the stern side of the tank. I have one of my vent holes almost in the center of the tank and it hits the wood panel covering the tank. Their seems to be more height towards the stern side of the tank.