Btw: I've read here:
So if you only print on PP, you basically have a 4-color-printer which text printing quality is not that good due to dye based ink, and which is slower at text printing than all-around printers like the iP4000 or iP4300. The photo ink just sits in the printer and is purged away with every cleaning cycle.When a photograph is printed on plain paper the BCI-6PC (Photo Cyan) and the BCI-6PM (Photo Magenta) are never used. When printing on Photo Paper that has been selected in the properties then these two ink tanks are used.