Cloudy water after opening and TA raise

Apr 3, 2012
9
Hey all,

I finally opened up my pool this weekend, my first time ever. I have a few questions, so I will give the break down of what I did. I am fully adopting the BBB method from the start, so I stocked up on my chemicals from Sam's club, and got to it.

To start off, the pool had been sitting for many months before I purchased the home. The worm infestation in the bottom was disgusting. My initial readings showed zero chlorine, therefore my first step was to add about 2.5 gallons of Clorox. This brought my FC to ~20. The rest of the readings looked like this.

Fiberglass
10,000 gal

TC: ~20
pH: <6.8 (less than the kit read)
TA: 0
CH: 260
CYA: 100+ (The previous owner used trichlor pucks exclusively, so I am guessing it is high, but couldn't get an accurate reading. This may be due to everything else being out of whack?)
Borates: 0

After shocking, I vacuumed, swept, and cleaned everything before my next step. I also washed out the filter after vacuuming, which was quite nasty. My next step was to bring my TA up to around 70. I used pool calculator to add 164 oz of baking soda. I added this over the course of 6 hours, a little at a time, brushing the sides and bottom in between adding. After running the filter for 5 more hours after the last addition, my TA read 80.

In the mean time, I took a sample of my water to the pool store to have them check it. (I was just curious how their numbers looked compared to my TF100) They showed I had a CYA of 25. Everything else was similar to my tests +/- 10. Why would my CYA be low there, when I was getting well over 100. It had a very heavy precipitate forming when I added the solution to the sample bottle.

As of 20 minutes ago, my numbers looked like this.

FC: 11
CC: 1
TC: >10
pH: <6.8
TA: 80
CH: untested
CYA: untested

My TA is now where I want it, next I will start adding Borax until I get my pH up around 7.5. My chlorine has fallen very slowly over the past 2 days, just now getting to around 10. I did have a little CC, but I assume it is from all the cleaning and stirring I have been doing. Does it normally take this long for TC to fall after shocking, or is my high CYA making it fall slower? (It was in full sunlight all day, too)

After adding the baking soda, my water has went cloudy. It was perfectly clear this morning when I started. I am wondering what my next steps should be. Shock again? My TC is still at 10. I want to add borax tomorrow, to get my pH up. I am also concerned about my TA going high when I add the borax. I would like to get my borate level around 30 for its benefits, but how can I do that without increasing my TA dramatically?


If you made it this far, I apologize for the book I have written. :eek: I will break it down into questions.

1: Could my initial low TA and pH, combined with high TC give a bad CYA test result? If so, why did I get 100+, where as the pool stores spectrophotometer showed i had 25ppm?

2: Does it sound normal for TC to take 2 days to fall from 20 to 10ppm when in direct sun all day?

3: Could the addition of baking soda be the cause of my cloudy water?

4: Is my next step adding borax to increase my pH up from <6.8. (Slowly of course)

5: How do I get my borate level to ~30 without raising my TA too much, or should I not worry about it?

Whew, this is fun stuff. Sorry for the long post!


-Nick
 
Hey, Nick,

First I would suggest you drain and refill half of your pool water to get your CYA down to about 50. CYA of 100 is virtually impossible to manage.

Once your CYA is down to 50, retest your TA. If it is truly zero, bring it up to 60ppm

Next, fix your pH. get it up to 7.2 Using 20 Mule team Borax.......don't worry about your TA....it'll not change much.

Disregard pool stores test results. Trust your own testing. You are far more accurate than the pool store.

Does it sound normal for TC to take 2 days to fall from 20 to 10ppm when in direct sun all day?
Yes

Get those parameters in line and then let's see if you need to shock your pool. Probably not, but let's get TA. pH and CYA fixed before you do anything else.

Don't get ahead of yourself. Spend some time in pool school (ABC's of pool water chemistry) and find out what normal ranges are. Let's get those three items fixed and then post results and we'll go from there.
 
Dave,

Thanks for the quick reply.

My TA was zero. I added sodium bicarbonate until it reached 80ppm. I am in the process of adding borax until I am up to 7.4. It was only after I added the sodium bicarbonate that my water went cloudy. I was wondering if it needed more time to dissolve (I added 10 pounds!)?

The CYA reading that I initially got was around 70, but I can get one less than 100 last time I checked. I decided to wait until I got my pH and TA under control before testing again. As I said, the pool store said it was 25ppm. Obviously, I dont trust it, but their other tests were very similar to my readings, so I have no reason to think it was an extreme outlier either.

I am going to wait a few days and let things settle down. I shocked it again with a gallon of Clorox, as we have a storm coming in tonight, and I dont want everything blowing in there and causing a problem. I will try the diluted CYA testing technique and see if I can get a more accurate reading.


-Nick
 
When adding baking soda to a zero TA pool, much of the bicarbonate will become carbon dioxide. To minimize subsequent TA rise when increasing pH, aerate as much of the carbon dioxide out as possible, because any remaining carbon dioxide will act as a buffer, which will increase the amount of pH increasing chemical needed. Also, the excess carbon dioxide will turn into carbonate alkalinity as the pH rises.

Retest the cyanuric acid by first diluting the sample with 3 parts tap water to 1 part pool water, and then multiply the result by 4.

Are you sure that you initially added baking soda and not sodium carbonate?
 
Seems like you are adding a lot of stuff to your pool if your CYA is really too high. You may just end up dumping it all down the drain if you have to replace water to get the CYA under control.

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HCO3- + H+ --> H2O + CO2(aq)

Bicarbonate + acid (hydrogen ions) --> water + dissolved carbon dioxide.

CO2(aq) + OH- --> HCO3-

Dissolved carbon dioxide + hydroxide --> bicarbonate ion

Dissolved carbon dioxide is a form of total acidity, which buffers pH rise. Total acidity is the opposite of total alkalinity. Total alkalinity, technically, only measures buffering against pH drop.

Interesting fact: An average bottle of Champagne contains 1.0 to 1.3 gallons of carbon dioxide.
 
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