Your first two questions seem to be directed at Heartland.
Even though this daughter board is "Ask The Factory", that is kind of a misnomer as to what it really is. The factory does not actively follow this board.
Hint; maybe time to rename this board slightly????
Half the responses people get when first time posting here is that the "factory does not monitor it".
Unless your Cyclone is built different then every other Cyclone, I would think that:
Grey #1 is for the shower and bathroom sink.
Grey #2 is for the galley sink and the washing machine (since your washer would be in the garage).
Unless tank locations have changed they should be:
Grey #1 & black are forward under the basement compartment, mounted lengthwise front to rear, side by side
Grey #2 above and behind the axles.
No interconnection of the grey tanks except at the 3" sewer drain outlet.
All the tanks are on the same relative level on the two axle Cyclones, as we have no drop frame.
When the grey tanks are full you should notice a few things.
For the shower/bath tank, when full the bathroom sink will start to drain slow or maybe not at all. The Shower may start to build up water in the pan. Both are clues the tank needs to be drained.
For the galley, the sink will start to drain slow or not at all.
There are no physical connections of the fresh water supply and the waste tanks.
Do you have cats? We have had at least one member whose cat turned the sink faucet on and drained the freshwater tank. 100 gallons of water has to go somewhere and the galley tank only holds 40.
Kids???
The standing water test in the sink may or may not yield the results you need.
The tank is vented to the roof.
If you have a full tank and then fill the sink, it will continue to drain, although very slowly until you reach an equal level of water in the sink and water in the vent pipe going to the roof.
That could take some time. And if the tank, sink drain and vent pipe are in proper condition it will yield only that you have no leaks.
If you were to fill the tank that full, and found your vent pipe was leaking and not installed properly, you would not be the first.
The tanks are all below floor level. So, I would start by careful examination of all the sink plumbing at least up to what you can physically see before it goes through the floor.
