Black Water waste. HELP!

[ttmott]

You can put water into the tank through the pump-out deck fitting. Just don't stick your fresh water hose down into the pump-out deck fitting!!!! You might want to have a dedicated hose for that - or at least a short extension to screw onto your fresh water hose.

I can't do that; the minute the water level in the tank covers the siphon tube it backs up and overflows the deck port. Maybe it is the air vent restriction through the filter.
The only way I can add water to the tank is through the heads or possibly pull the head discharge fitting out of the tank and fill there.

 

[Lazy Daze]

I can't do that; the minute the water level in the tank covers the siphon tube it backs up and overflows the deck port. Maybe it is the air vent restriction through the filter.
The only way I can add water to the tank is through the heads or possibly pull the head discharge fitting out of the tank and fill there.

I think you're right. If the water is backing up the fill tube then that means the air isn't escaping from the tank quickly enough. Most likely, the filter is slightly clogged. I've done this many times (with a filter in place) and it's never been an issue. Try unscrewing the tank side of the filter as an experiment to see if it then works. But the filter shouldn't be causing enough of a restriction to prevent you from filling.