Couple things.
-The pots you are using- clay pots- are those the ones with built-in drain trays? If so, you MUST re-pot or you will end up with drainage problems, pH problems from sodden peaty soil, and likely root rot. Trust me on this one.
-The soil. Expert Gardener is the Shultz brand soil. Some types contain ferts. Read the label and see what the NPK is listed at.
-The new growth. It looks good. I don't see a reason to do much besides re-pot into a pot with correct drainage. Low leaves do that often. It looks like a K or Ca deficiency, but those are old leaves that get little light AND are close to the soil surface so they are in a more humid part of the plant and get less air circulation.
Remove the leaves when they come off with a slight tug, and watch to make certain that the next set doesn't show the same symptoms. But you NEED to re-pot and let your soil dry out slightly between waterings. Oh, and use tap water.