I was wondering if anyone attempted installing a pipe to the holding tank and a macerator.
It should be fairly easy to do: install a y-valve in the pumpout line, add a hose to go to a macerator pump, then from the macerator pump to a below waterline thru-hull. However before installing a macerator pump, you'll need to know where it's legal to dump a tank.
I get the feeling from some of your terminology that you're fairly new at this, so I--and everyone else here too--will be glad to "translate" anything unfamiliar to you. We'll have you speaking "marine" in no time.
Also wondering if the deck pump out has a tube that goes into the tank.
There should a be a hose that connects the tank discharge fitting to the deck pumpout fitting. It does not go into the tank. However, if your tank discharge fitting is on the top of the tank, there needs to be a pipe inside the tank that goes to the bottom of the tank. Is there a specific reason why you're asking?
--Peggie