Hoping to get help with my 6 year old bamboo plant. Its approx 5 feet tall potted in a 18 inch diameter floor pot with potting soil. It continues to get dead leaves (see attached picture). In the past I've tried changing the amount of light & water it gets and also have changed the soil but to no avail. Do anyone have any ideas on what might be causing this? I've been considering getting a meter to more tightly measure and control light, moisture, fertility, pH and temperature. Would this help or is there something else I need to do?