Why do you want a gray water (galley, bath and shower water)
tank? Gray water can legally discharged directly overboard in all
waters except for a very few places...all of which are at least several
hundred miles from you if you're close enough to Ed to buy a boat from
him. Plumb your sinks to drain directly overboard...and your
shower too, unless it drains below the waterline. If it does, you'll
need a sump and sump pump for the shower only.



"I have read about air to the system to keep oder down. But how much air gets through a 1/2" vent hose anyway? "



You've bought my book, but apparently you haven't read it yet if you
plan to use only 1/2" vent. You need at least 1" vent...1.5"
would be even better...an aeration system in the tank better yet.
Hopefully you haven't already bought the tanks... but if you have, it's
no big deal to install new vents.



"Do I put a valve in the system so I can pump grey water or Black water out serarate?"



No. If you're determined to have a gray water tank (which btw requires
even MORE maintenance than waste holding tanks to prevent odor and
clogs), it should be plumbed completely separately from the
holding tank tank...no common plumbing at all, not even the vent...to
prevent e-coli contamination of sinks and surrounding areas in the
event of a backup. Use the same Aussie hose for it that you'll
use for your sanitation system.



However, for your use, I'd forget the gray water tank and go with a 30 gal waste tank.



You haven't even mentioned a fresh water tank...I'm assuming you DO plan to have one.



You can't use the macerator at all....'cuz it's illegal to dump a tank
in all U.S. waters. You must be in open ocean at least 3 miles from the
nearest point on the whole US coastline to dump a tank legally.



Which manual toilet did you buy?



I'll be glad to walk you through the installation. But first, READ my
book...most of your questions are answered in it. Make notes,
questions...then we'll take it from there.



Btw...it has nothing to do with plumbing...but you DID buy a CG approved fuel tank?