One more thing- overwatering can cause acidic soil. If the soil stays too moist for too long, u end up with some seriously acidic dirt (like 4.5). That's one of the reasons why we don't re-use soil. Remember, each point on the PH scale is 10x the acidity or alkalinity. At 4.5, you are about 20x more acidic than you should be(I keep mine anywhere between 6-6.5), and your plants will DEFINITELY be exhibiting symptoms of multiple deficiencies.