Looking for advice

First time grower…My bottom leaves are slightly yellow and curling up on the edges, is that a sign of stress?…is it over or under watering?? I give them 1/3 cup every 3 days. Soil PH is at 7.5, should i get that under 7? (Don’t mind my makeshift straw brace, had one over stretch)

First time grower…My bottom leaves are slightly yellow and curling up on the edges, is that a sign of stress?…is it over or under watering?? I give them 1/3 cup every 3 days. Soil PH is at 7.5, should i get that under 7? (Don’t mind my makeshift straw brace, had one over stretch)