Dont let them sit in runoff water. That will throw off the soil ph. Runoff water is really acidic and the ppm is crazy high. Its bad for the roots.
Try to elevate the pots, so that they aren't sitting in water. Or use a sponge to clean up the runoff water once your done watering.
Ive seen the same symptoms on some of my plants, when they sit in runoff water. I am pretty diligent about not over watering and keeping the catching trays dry.