I had neglected my water chemistry for a couple of months, except for free chlorine, whidh had been easy to maintain. Then I started getting a black, soft, precipitate in the deep end of the pool. So, I checked and found pH at 7.0 and TA close to zero and CH close to zero.
So, I added 15 lbs. of sodium carbonate anhydrous. I did not pre-disolve it (as I now understand I should have done). Pool is in-gound 20,000 gal. Result: water, after 24 hours is still cloudy (was clear before adding the NA2CO3). Now tests at pH 7.6 and TA 100-110.
What should I do and what has caused this?