Is there a chemical answer to black water tank?

[what_barnacles]

Originally Posted by Comodave

Even using freshwater and not enough oxygen the tank will stink. You can add chemicals, but the real solution is add air. We did the Groco Sweetank and never added any chemicals at all for 9 more years that we owned the boat without any stink.

question: Did you need to modify the tank vent to run to both port and stbd? I havent seen too many boats with both sides vented. (check their illustrations)
https://www.groco.net/products/marin...dor-prevention

[dhays]

I have known plenty of folks who have installed Sweetank with only one vent, not port and starboard and had no problems.

[Comodave]

A Sweetank works with one vent just fine. The two vent arrangement is for natural air flow through. If you are replacing a tank, I would go with two large vents. If using the existing tank, I would install a Sweetank or make something similar. I put in a Sweetank and it took about 45 minutes to install it. Only hard part was pulling thr trigger to drill a 2” hole in the top of the tank... After 2 hours the stink was gone completely. I did install it when my dock neighbors were gone because the first 2 hours were quite stinky until the aeration was complete.