Added handful of Dolomite lime to lower ph but no results yet. Planter is about 3 gal. How much would you guess to add?
1-2 tablespoons. Go easy with that stuff, it will take weeks to work and can raise the KH of your soil by a bit.....
I would say you are beginning stages of a manganese / iron deficiency. Probably the most common under-diagnosed problem that happens before all of the cal/mag, N and P and K lockouts. Especially in the tips......
Just yellow tips? Are the main veins still green? Or are they losing color, [taking a picture is best to remember for periods over 24 hours]
How are your older leaves. They should stay unchanged. A few changing is somewhat normal, but I can't tell for sure.
^ Those are the normal symptoms of a iron/manganese deficiency.