Fairly sure we sacrificed a whole idol of the stuff. And if it takes longer for larger amounts than that, once we've cleared out all the stuff inside of a fortress, sanctifying the grounds, watching over it and letting it convert into regular stone basically means we can have the tritons garrison a free fortress, no construction needed, likely using all the sacrifice juice for some free defenses geared toward anti-aberration tactics. Or better, suborning their wards...
learning from them. After we've purged the unclean from it, obviously.
Edit: Though I guess the silver spikes would be faster... fiiiine. I'm just tired of diversions.