Anyone ideas to what may be causing the lower leav...

don't water so much.. water until 20% runoff.. then, wait for 1" to dry before watering again -- ferts or not. continue to alternate or every third for your fertilizer.. find a good concentration that works out at that frequency -- trial and error. just give water-only.. don't flood it.. it'll work itself out if you overfed in no time.. Doing the above will keep concentrations in your substrate in check. once you do this fora bit... re-assess .. if it continues to nosedive, it's something else that requires more thought. In general, yellowing from below from tips-in is N-def, but many things cause yellowing and based on your description, sounds like a bit too much water / possibly too much nutes and once that's in line, you may not have a problem at all. pH 6.5-6.8 ish is great for soil, unless your nutes say something else.