It suddenly came to my attention that the combination of tray watering while using a calcerous substrate for Mexican Pinguicula could have dire consequences if you don't think before you act.
I really feel a tad slow for not thinking of this in the first place, but, it would be a really good idea to keep Mexican Pinguicula with a calcerous substrate in a tray reserved only for these pings. Water and sitting in water leaches some of these minerals and calcium into the water source which in effect could be and most likely will be reabsorbed by other pots sitting in the same water. ie. a VFT would not like coral or vermiculite usually added into it's substrate, therefore, don't filter the water through these items.
Just to keep it safe, only put the same media types and plants of the same requirements into the same trays.