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I'm guessing it comes in a blue tub with yellow writing. if so, it's an excellent product. As I have a caravan and don't have a grey water tank, I usually plug the outlet pipes and pull the water with the solution through the whole system... leave for the 24 hours and then flush through twice. Cleans all the outlet pipework as well. Excellent product.

That’s it all right, I filled the system yesterday and pumped it through the sink, whb and shower to have charged them pipes then left it overnight. Then tonight I pumped it all out through them into the grey waste tank with the drain open and drained out onto the yard. Then flushed through twice, then filled the tank again with fresh water, might just flush that through again tomorrow and refill with fresh water.

On the toilet cassette question another option is to get a cassette fresh up kit. This basically is a new replacement cassette and a new toilet seat and cover (Thetford models). This can be replaced every few years or as required. 
 

Thank you Chris, the cassette is in good order, no smells or anything I don’t think the last owner used it. But good to know about the kits. 

Yes - the pink stuff is just a fragranced additive.  You can use Biological washing liquid in the loo.  Or the green environmentally friendly option.  Coke is good for the waste tank.  Avoid Milton for anything other that a wipe down of surfaces etc. - it can destroy the heating elements in the Truma. 

I've been using the bio washing tabs in the cassette all last year with no probs, and a fraction of the cost of the chemicals... the lads above are right, the pink additive is just a fragrance......