Seconded. Been there, see it, done it.

Best to sort this before it decides to set in all the pipework, like mine did. I spent a freezing cold afternoon some years ago, disconnecting all the pipes and blowing them through[1] before removing and cleaning all the jets. Then it was a case of shoving a hose into the tank and turning it on full chat to flush the crud out.

I've always syphoned out the tank contents when swapping from summer mix to winter and vice versa since that unpleasant experience.

[1] Very fortunately it was one of the more accessible ones that required a wire coat-hanger shoved through it. If that had been the tailgate jet pipe I'd have been properly stuffed.