Right now Im using 50% Noodlers bulletproof black and 50% Waterman black. I seem to recall reading somewhere that Florida blue mixed with Noodlers can cause a precipitate to form in the ink. Is this true?

I would say in general crossing brands is asking for trouble. You seem to be getting away with it in this case but I wouldn't say its a safe bet most of the time.

Too many changes in pH and other chemicals.

Thanks for the reply Rapt. I honestly figured that mixing Noodlers and Waterman would be ok, and so far there have been no problems other than what already comes with Noodlers territory(nib creep,etc)

I tried to reply and the server hiccoughed.

I have mixed WP black with Diamine inks with no problems. In fact, had such a mix (Woodland green and WP black) in a pen that I forgot about for over a year. When I discovered it, I filled the pen with water and wrote out what remained.

I recommend mixing in separate containers and letting it sit for a few days if you're particularly concerned about it.