cloudy pool

[perryy]

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?

 

[The Mermaid Queen]

Sorry, cannot help you at all, but Welcome to TFP!!

 

[chem geek]

For the pH and TA to have dropped so low, I suspect you have been using Trichlor tabs/pucks. If so, then your Cyanuric Acid (CYA) level may be very high so I suspect that the cloudiness could now be a nascent algae bloom. If your Calcium Hardness (CH) were normal to high, then I would say that the cloudiness was due to the sodium carbonate addition since that is typical (since it is high in pH and TA, especially where locally added), but with low CH the cloudiness is more likely to be algae.

However, I am surprised by the very low Calcium Hardness. What sort of test kit are you using? If test strips, then those can be inaccurate and I suggest you get the Taylor K-2006 test kit (from Taylor, Leslie's online, or some pool stores, though do NOT get the K-2005) or the TF100 test kit from tftestkits.com here.

Do you know your pool's CYA level? You can start off right away shocking to 15 ppm FC and adding chlorine as needed to maintain that level until you get more information.

Richard

 

[perryy]

After another 24 hours, the cloudiness has dissipated about 95%. I tested more parameters, using a Taylor test kit: Free Chlorine 2 (my floater was out of the pool today), pH 7.6, TA 120, CH unmeasurably low, Cyanuric acid over 100. You are correct that I've been using the TriChlor pucks, not realizing that I was adding to the cyanuric acid level.
So, I'll add calcium chloride to get the CH up, shock as you recommend. Should I pump out some water to reduce the cyanuric acid?
Thanks for your help.

 

[JasonLion]

Yes, you need to replace water to get the CYA down. That will bring several of your other levels down as well.

 

[perryy]

OK, I replaced about half the water in the pool. Readings, subsequently, were FrCl 0.5, pH 7.1, TA 40, CYA 70.
I added 5 lbs. soda ash - next day readings were FrCl 0, pH 8.0, TA 90.
Yesterday, I added 4 gal. of 6% bleach. Result today: FrCl 6, ph >8, TA 80. Throughout, CH has read zero with the Taylor test.
So, what should I do now? Is there a need to get the Cl up to shock levels, or should I concentrate on getting the water balanced? The water is clear. Should I add Sodium Bicarb now to raise the TA, since the pH is high?