The difference rice makes! You probably think that I am raving, but because the wallet is a depleted at the moment I use the rice pot to clean my expansion tank on the inside. I have chosen rice and split peas because they have rough edges but are softer than the plastic of the tank. We started of like this:
tankje-2  tankje-1

The rice before I started to boogie:

Tank after shaking and cleaning the outside:
tankje-4  tankje-5

Now just wash everything in soft soap and then this tank will be very useful for the time being.
And the rice? Chuck it in the bin.