Waste water tank cleaning

This is something everyone will have a view on as everyone does it.  When I sterilise & descale the freshwater tank, which I normally do with citric acid, I use the same solution to sterilise & descale the internal water system including the HW tank.  It all eventually goes into the wastewater tank and toilet cassette where I leave it for as long as I can.  Ideally I make up enough solution to fill both the wastewater tank and toilet cassette.  I collect the solution in a bucket when I drain the HW tank and pour it into the wastewater tank.  If the wastewater tank isn't completely full, I take the van for a drive to slosh the contents around.  When I empty the wastewater tank, I give it a good flushing with mains water forced into each plug hole with the garden hose to remove as many bits as I can.  If the wastewater tank is heavily soiled, the bits can clog up the drain tap.  If this happens mains water fed into the tank through the drain tap should clear it.  I have found that the tank may still not be completely clean and after just one trip it will get more dirty.  So at the end of every trip before leaving the site I fill the kitchen sink with hot water and dissolve a dishwasher tablet in it.  I then drain it into the empty wastewater tank and drive home with it sloshing around.  Once home I drain the tank and again give it a good flushing with mains water.  I also put plugs in all the plug holes when the van is out of use to stop smells getting into the van.

Something else I have started doing of late is that when I empty and flush out the toilet cassette at the end of a trip, I put toilet fluid back into it ready for the next trip.  This prevents mildewy or worse smells developing in the tank whilst the van is out of use.

I don't use it when the van is in use but when not going to be used for a few weeks i use the cheapest bio laundry gel with water in the cassette. It keeps it squeaky clean and smelling fresh.

Same no bio pods are all we ever use in the cassette, still have the pink stuff in the flush tank
Works really well, zero odour and total liquidation of the contents