We live in a part of the world (coastal Canada) where overboard discharge is legal, and in fact is the norm. We just bought a US boat on which the overboard discharge valve is seized shut, so if we are gonna use the head, apparently we are gonna use the holding tank. It's probably time to be start being a bit more environmentally sensitive anyway. We do have a pump that will allow us to pump the holding tank overboard, or we can pump out at the local facility. But, having zero experience with holding tanks, I have a couple of questions:
1) Do people add something to the holding tank to assist with the biological processes of decomposition? Or is this dependant on the length of time between pump-outs?
2) Our tank is only 15 gallons, how long is that likely to take the 2 of us to fill? (2 days, 2 weeks, ???) (I'm pretty proficient at using the urinal in the stern of the boat, the Admiral hasn't mastered that one yet
3) The boat has been on the hard for 2 years, I would like to pump some mineral oil thru it to lube the seals, but I think I read somewhere that the oil is not good in the holding tank. Any advice on this?
4) What is the process at the pump-out facaility? Is it just a matter of sticking the pump hose in the deck fitting and sucking the contents out of the tank? (that is waaaay to easy...)