Ice in Black Tanks?

I had seen a black tank cleaner wand thing once in a camp store, just a piece of PVC pipe with a cap and a couple holes drilled in it to make nozzles, and of course outrageously priced, so I made myself one for about $5, most of that for the hose adapter fitting. It has 3 holes drilled in the side of the pipe and it goes straight down in the toilet and into the black tank. Hose turned on full blast provides three strong sprays, and usually the second filling of the tank clears the sensors, and any additional water comes out clear and colorless. Never been tempted to try the ice technique, although I've read about it here for years.