Agree, make a trip for a good regulator. At times water pressure in CGs will change and this way, you're covered. Also the pressure test.
Re the current mess you're dealing with....agree that is sounds like you've got a leak somewhere in a line or your grey tank is full. Generally, when the grey tank is truly full, the water will overflow into the shower. When that gets full, it's over the top. I'm not understanding the "plugs"....are these just the standard "stoppers" that come with all the sinks and showers/tubs or something that was added? Purpose??
If you're not being extremely miserly with your water, you can fill a grey tank before you realize it. The downside of leaving it open is that you could get odors from the sewer system itself. Closing it will stop that but you'll have to be vigilant about making sure to dump the grey daily. Don't trust the sensors for the tanks....they're nearly always completely wrong. Our brand new TT showed a full black tank before we ever used it. Likely a sliver of some building material on the sensor. It's remedied itself, but we never trust it. You'll learn with time what your usage is and when to dump.
