shan

Hello all, Hubby is out of town which puts me in charge of the pool. usually our water is pretty easy to keep adjusted but I am having a hard time for almost 2 weeks now. My chlorine is a teeny bit low but ok. My TA and PH are extremely, extremely low. My pool company person told me to add baking soda which I did. I have gradually added about 12 pounds of baking soda over the last 10 days and nothing has changed. My steps are starting to get a brown ring at the top and my usually white main drain is also starting to look brown tinted. My pool is inground, about 24,000 gallons. Water is crystal clear-no algae or slickness that I can tell. I have never had to be a chemist when it came to the pool so I am lost. Any help at all will be appreciated! Shannon