I had a couple jars that started to get the slightest hint of kahm yeast, I shook the jar up coating everything again with the brine and lactic acid...which effectively stopped it. The yeast doesn't like the harsh environment of the brine/acid, so it grows on the very surface...which is also where the highest concentration of O2 is likely to be. Giving it a shake ensures that anything even thinking of growing on the surface, doesn't. So as long as you don't open it, and give it a shake every couple days at first, then every few weeks/month later, you should be good. Of course if you use an airlock you might not be able to shake it up, it will just plug it up. I don't personally use airlocks, I just leave them cracked a tiny bit to vent during the fermentation (first couple weeks), then crank them down when its done. As long as its not too loose, the positive pressure inside the jar from the fermentation will ensure that gases only flow out, not in.