Originally Posted by nitecapt
It's a fresh water system, with a dedicated fresh water tank to supply the toilet. I'm looking for a safe product I can put in the fresh water supply tank much like you put in your home toilet tank at home.
The short answer to your question is, there is no product you can add to the tank that will provide perfumed colored water to the toilet. And don't even think of hanging anything the bowl either. If your flush water gets funky, it means it's sitting in the tank too long, not getting changed often enough. 30 gallons is a LOT of flush water...10-12 gallons is enough to keep the water moving through the system.
Toilets designed by the mfr to use pressurized flush water can be safely connected to the boat's potable water system, so it's not necessary to install a separate flush water tank. You'd have also needed a water pump for it 'cuz they only use pressurized flush water. So installing a separate flush water system for a toilet DESIGNED to use fresh water was a whole lot of unnecessary extra expense.
If it's actually a sea water toilet (unlikely if I recommended it), if your flush water tank is connected in any way to the main water system--if you didn't install it as a completely separate system including a separate fill--your potable water is still exposed to contamination from the toilet.
So if you're trying to cure funky flush water, the RIGHT solution would be to remove the flush water tank and install the toilet as it was designed to be installed....or a much smaller tank, if the toilet is actually a sea water tank.
Btw, NEVER use household chemical bowl products in a marine system...they're highly destructive to rubber and also hoses, many are also corrosive. Also never use any cleaning products that contain bleach or chlorine (I'm sure you already knew that), pine oil cleaners, or Lysol etc unless you want to change hoses and rebuild the toilet every couple of years. Use them with care, even at home, because most contain chemicals that can be lethal when combined with other products..the following can be a real eye opener:
Clean House Clean Planet - Karen Logan - Google Books