Filtering dirty water for zircon has a 20% chance to gain titanium ore on top of the chance for zircon (which is already higher than any other filtering recipe). Filtering specifically for titanium has only a 5% chance to gain titanium ore. You could just void the zircon in a crusher and keep the titanium, or process it further to get more byproduct titanium and void the resulting zirconia/enriched zircon. It's probably not a real problem since the amount of ore from filtering is pretty tiny either way, but there does seem to be no reason to ever use the titanium filtering recipe. Is this an oversight, or is there some reason for this that I'm missing?

Thanks. The idea is that titanium shows up with Zircon a lot. However you're right that the situation with dirty water in K2 is a bit strange, and sort of pushes people towards choosing only the zircon recipe. I'll think on it a bit more.