Holding Tanks

This may be a dumb question but here it is:  Why does the PC have a black water tank capacity of 35 gallons and the grey water is only 23 gallons.  This is our 6th RV and usually it is the other way around i.e. grey water tank almost twice the size of the black.

What are the advantages of this setup?  It seems to me a couple of showers and wash the dishes and the thing will be full of grey water while the black water tank is still almost empty.

When you are travelling/camping how do you manage your tank?  Do you just dump the grey water every day and the black when it gets more than half full?  Do you dump the grey water into the black tank by equilizing them?

We still haven't had the rig out yet so we have just tested the operation of it by dumping fresh water into the tanks.

as many pces are owned by beer swilling, stinking  tiny grey tanks are just fine

maybe folks keep more water in black tank in order to keep from playing Pharaoh and building pyramids....an older post mentioned piles of stuff so don't yell at me... 2o2they may want boats instead

maybe that size tank fits in that spot
  :coolas i am now cooled off, back to packing for our visit to see son unit
i, too, would like to know the real reason
i have other ideas...they can wait til billy and i are jawing at the campfire 
kevin

Ann and Bob

The size of the tanks (35 black, 23 grey) I think is based upon the plumbing lay out plus where the tanks can be mounted under the PC.  The 2350, 2551 and 2552 have smaller grey tanks and larger black tanks.  All the other models are just the opposite.

Managing the tanks depends upon the campground.  If full hook ups are available I connect the 3" sewer hose, open the grey tank and keep the black tank closed.  When the black tank needs dumping I close the grey tank and let it fill up a little before I dump the black tank.  After I dump the black tank I use the water hose connection on the San-Con to flush the black tank.  Once the black tank is flushed I close the black tank and add a couple of gallons of water to the black tank, add any chemicals and start the whole thing over again.  The finale step is to open the grey tank for one last flushing of the 3" hose.  This is just me - I never have the grey and black tanks open at the same time (do not want any cross contamination) again this is just me.  If the campground does not have sewer hook ups I keep both tanks closed.  When the grey tank fills up I use a blue dumper to empty it.   It usually takes about two weeks before I have to dump the black tank.

Barry

As best I know, the placement of the stool in the individual models is what dictates what tank is used for what (the tanks only fit the frame in one way).

As for cross-contamination; that's only a concern if you let the black tank contents enter the gray tank.
I dump the black tank, shut down the sani-con (or shut the manual 3" valve) and then open the gray to allow water to backflush into the black. Then I dump the black again and repeat the process once.
Finally, I shut the black and open the gray to let that water flush out the hose.

Remember, do not leave the valves shut when flushing with city water.

Also, you can increase the gray water capacity somewhat by letting it flush into the black tank.

Been doing it this way for many years and it hasn't made me an Egyptian yet.

Thanks for all the input.  The bypass has me confused.  Do you use the bypass to drain the grey water and use the Sani-Con hose or do you use the 3" emergency dump hose connected to the sewer.  I think that may be where I am getting confused.

Do you use the 3" emergency dump hose and then open the manual valve which would put the water out that exit?  Now that makes sense.  I have been having trouble understanding how you put the Sani-con hose into the sewer and open the valve.  Which valve?  Is it the electronic valve opener? or is it the manual valve opener.  And if I have the Sani-Con hose in the sewer and I open the manual valve won't the grey water come out the 3" emergency opening?

Sounds like it will be easier for us to just use the Sani-Con pump and pump the grey water out that hose.  The other way you are now dealing with an icky 3" dump hose which is the purpose of the Sani-Con.....to do away with it.

Guess I need someone to spell it out for me exactly step by step how to do it.

Anne

This is a copy of my reply on another post that applies to your question.

We too have a 2350 with the gray tank being the smaller 23 gallon one.  Given we almost exclusively dry camp, the gray tank always fills long before we run out of fresh water.  To buy time, (per Phoenix USA instruction) I flood the gray water into the black tank by first opening the gray tank valve, then the black tank valve, wait for the gurggling sounds to quiet down, then close the black valve, and finally the gray valve.  I usually do this once between every fresh water fill-up, so it is done very frequently during trips.  If getting very close to empty with the fresh water tank, sometimes I have to do it twice before dumping.  It is no big deal.  Only an inconvenience.

Given we don't do #2 in the bathroom, without fecal matter to be concerned about, I am tempted to keep both valves open all the time, but worry that if sewage ever did back up into the shower pan for any reason, it would be contaminated with urine.  It does seem a remote possibility which has me tempted.  Also, I think some rigs of other brand motor homes, have the shower pan dumping into the black tank.