Answer: Once a day is certainly too often. Exactly how often is not up to me to answer since I don't know the maturity of your plants, the soil type, nor the exact climatic conditions. What I would recommend, however, is for you to hold off on watering until you see the plants begin to wilt slightly. The idea is to figure out how many days you can go between waterings and then wait that many days less one, before you water again. When you do water, provide enough to soak the plants deeply. And use a mulch to maintain a more even water level. If the lower, oldest leaves are the ones turning yellow, yes, it sounds like simply a case of too much water.
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