Groco SweetTank
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Groco Sweetank is a holding tank aeration system
It has nothing to do with the toilet, it's installed in the holding tank...so it makes no difference what brand or type of toilet sends the waste to the tank. The complete manual is here: http://www.groco.net/parts/data/622.pdf When installed, operated and maintained according to directions--which include running it continuously 24/7/365 (except during winter layup, of course)--it eliminates odor out the tank vent completely without the need for any tank products. Because it does have to run continuously, there has to be a source of power to keep the battery charged, so it may not be appropropriate for boats on a mooring or in a slip without shore power. List price is about $250...I've seen on sale as low as $150.
It has nothing to do with the toilet, it's installed in the holding tank...so it makes no difference what brand or type of toilet sends the waste to the tank. The complete manual is here: http://www.groco.net/parts/data/622.pdf When installed, operated and maintained according to directions--which include running it continuously 24/7/365 (except during winter layup, of course)--it eliminates odor out the tank vent completely without the need for any tank products. Because it does have to run continuously, there has to be a source of power to keep the battery charged, so it may not be appropropriate for boats on a mooring or in a slip without shore power. List price is about $250...I've seen on sale as low as $150.
We tried one
We have one, in our ongoing efforts to absolutely minimize the stink from the holding tank. Peggie's book refers to the benefits of aeration, done properly (more than just a fish bubbler). So the logic is there to support the product. After you get through installing it (which is no fun cutting hole in the holding tank), then you turn it on, and realize that the constant buzzing of the air pump must be isolated, lest the admiral throws it overboard. We run it as much as we can, but definitely have to turn it off occasionally, especially at night. We also bought Peggie's book, correcting several past mistakes (the one I like is using lube in the head each week to keep it working well; which apparently creates an oil slick in the holding tank that kills off all the good bacteria...despite our wonderful Sweetank trying desperately to supply lots of oxygen...to the dead little guys). I'd buy her book first, and follow her advice, and then see if you still need help from an aeration system. Any other questions, let me know. Paul
We have one, in our ongoing efforts to absolutely minimize the stink from the holding tank. Peggie's book refers to the benefits of aeration, done properly (more than just a fish bubbler). So the logic is there to support the product. After you get through installing it (which is no fun cutting hole in the holding tank), then you turn it on, and realize that the constant buzzing of the air pump must be isolated, lest the admiral throws it overboard. We run it as much as we can, but definitely have to turn it off occasionally, especially at night. We also bought Peggie's book, correcting several past mistakes (the one I like is using lube in the head each week to keep it working well; which apparently creates an oil slick in the holding tank that kills off all the good bacteria...despite our wonderful Sweetank trying desperately to supply lots of oxygen...to the dead little guys). I'd buy her book first, and follow her advice, and then see if you still need help from an aeration system. Any other questions, let me know. Paul
Against recommendations, I built my own system....
The "best" way of ventilating the tank is to have two vents for cross-ventilation. Each vent is run to a DIFFERENT side of the boat. This will ensure a positive cross flow because when the hull is at an angle to the wind, the air pressure on each side will be different. The air pressure behaves much like the sail with the air pressure lower on the side with the longer distance to travel. On our h40.5, the holding tank is located below the salon floor and there is no way to run two vents without having excessively long runs and/or unacceptably steep rises to above the water line. Hence, the only way to get more oxygen in the tank was to power ventilate it. I looked at the SweetTank system and decided that I would attempt to build a comparable system. A 12V air pump of sufficient volume was used and I designed an air plenum that would distribute the air across the tank. The hardest part of the project was to implement the entry into the tank so that the plenum could be inserted or removed (for cleaning if necessary) and yet be water-tight. I've used the system all last year. It works well, although I do add Odorlos to the tank at each boat arrival. My boat is on a mooring, so I do not run the air pump 24/7 as recommended. For the first hour or so of aeration, the odor out of the vent is potent. I plan to build a timer to run the pump 10-15 minutes each hour when I am away to eliminate that problem. The bottom line is that I feel the system will perform as claimed. I'm not sure it will eliminate the addition of the bacterial agent since I have not tried that. Running the air pump 24/7 may be necessary.
The "best" way of ventilating the tank is to have two vents for cross-ventilation. Each vent is run to a DIFFERENT side of the boat. This will ensure a positive cross flow because when the hull is at an angle to the wind, the air pressure on each side will be different. The air pressure behaves much like the sail with the air pressure lower on the side with the longer distance to travel. On our h40.5, the holding tank is located below the salon floor and there is no way to run two vents without having excessively long runs and/or unacceptably steep rises to above the water line. Hence, the only way to get more oxygen in the tank was to power ventilate it. I looked at the SweetTank system and decided that I would attempt to build a comparable system. A 12V air pump of sufficient volume was used and I designed an air plenum that would distribute the air across the tank. The hardest part of the project was to implement the entry into the tank so that the plenum could be inserted or removed (for cleaning if necessary) and yet be water-tight. I've used the system all last year. It works well, although I do add Odorlos to the tank at each boat arrival. My boat is on a mooring, so I do not run the air pump 24/7 as recommended. For the first hour or so of aeration, the odor out of the vent is potent. I plan to build a timer to run the pump 10-15 minutes each hour when I am away to eliminate that problem. The bottom line is that I feel the system will perform as claimed. I'm not sure it will eliminate the addition of the bacterial agent since I have not tried that. Running the air pump 24/7 may be necessary.
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