just bought a bottle of the blue one chem to try next week. it says on the bottle to be also used in the top flush tank aswell as the cassette, is this true? does it not give the flush water that horrible "chemical fragrant" smell? and does the flush water then turn blue and stain the toilet bowl? and what reviews do poeple have on one chem, do you realy get 40 doses? and is that small pre measured cap full enough for a cassette when its full? all reviews gratefully accepted. i use the local caravan showrooms own brand of blue and pink at the moment. regards, mark