Max shock level for a vinyl liner, has pink slime.

[JamesR]

Not my pool, a co-worker. Inground, 25K gallon, vinyl liner. 2 wall returns, no floor returns. 2 skimmers opposite ends of the pool and one pool drain in the deep end.
He says he has a pink/white slime issue and maybe some algae.
I had him bring in a sample of his pool water into work today and I brought in my TF-100 kit
TA = 110
pH = 6.8 to 7.0 (Very low)
CH = 250
FC = 2
CC = 4
Total CL = 6
CYA = 90. he has been using tablets/sticks in his skimmers.
According to the CYA vs chlorine chart, a CYA of 90 requires 30+ ppm of chlorine shock level. That is super high. Is it necessary to go that high? Will that damage his liner or the pump equipment?
He cannot drain and refill easily because he is on a well.
Suggestions for the pH and the shocking/cleanup?

 

[jblizzle]

Pink slime is VERY rare in a chlorine pool.

Following the SLAM Process process is safe for the liner. The CYA buffers the FC.

The low pH is a greater risk to the liner.

 

[AftonJeeper]

Pink slime makes me think of baquacil, make sure this pool wasn't a baquacil pool. More over in that sub forum here: Baquacil - Use and Conversion

People have gone as high as double the shock level for their CYA for 24 hours and had no ill effects on their liner or equipment. You need to remember that the [FC/CYA][/FC/CYA] relationship makes the water safer/better than have no CYA and a FC of 1-3.

The pool is safe to swim up to shock level. Have them bring pH to 7.2 before they start the SLAM Process. No need to test it after they start because a FC over 10 makes the pH test invalid.

 

[JamesR]

Definitely not a Baquacil pool.
Best method to get pH up to 7.2 without raising TA?

 

[jblizzle]

Aeration ... although that may be slow. Use borax or soda ash and it will not impact TA much. PoolMath will tell you impact at the bottom in the Effects of Adding Chemicals section

 

[JamesR]

Aeration ... although that may be slow. Use borax or soda ash and it will not impact TA much. PoolMath will tell you impact at the bottom in the Effects of Adding Chemicals section

The calculator says in order to go from a pH of 6.8 to 7.2, to add 116 oz of soda ash. The effects program at the bottom of that same screen says that adding 116oz of soda ash will increase pH by 1.01. That puts me at 7.9 ??? it also says that will increase the TA by 36, that would put it at 146. I must be missing something.

 

[Donldson]

I think jblizzle had a bit of a senior moment

Soda Ash raises both pH and TA significantly while borax raises pH significantly with only a marginal rise to TA.

 

[JamesR]

I think jblizzle had a bit of a senior moment

Soda Ash raises both pH and TA significantly while borax raises pH significantly with only a marginal rise to TA.

OK, but something is still not making sense to me. The calculator says to add 231 oz of borax to get the pH from 6.8 to 7.2. A 0.4 increase. The "effects" section says that adding that same 231 oz of borax will increase the pH by 1.01. Which one is correct?

 

[jblizzle]

Yeah, I had said just borax and then went back and added soda ash to my comment

Also, I forgot that things related to the pH and TA are iffy in the Effects area.

 

[JamesR]

OK, so the calculator should be correct? 231 oz of borax will raise the pH by .4-ish?

 

[domct203]

Yes, pool math is correct if you entered all your current levels.

 

[JamesR]

Great, thanks folks!!

 

[JamesR]

He added borax (too much) ?. pH is close to 8 now. Then he added 6 gallons of bleach and says his FC went from 2 to 1. CC went from 4 to 3.5. How is this possible? Cya is still 90

 

[jstephens1]

He is probably using guess strips which can’t measure over 5ppm

 

[JamesR]

I gave him my TF 100 kit to use

 

[jstephens1]

Testing error?

 

[lightmaster]

Assuming you have the volume of water accurately measured, and have checked your pH correctly, the main part of PoolMath will tell you the correct amount of Borax/Muriatic Acid to add to get back to your target. The part at the bottom has this warning below it about pH:

Note: pH calculations are not exact. These numbers are only suggestive of the relative magnitude of the pH change you can expect. Small changes, +-0.4, with pH between 7.2-7.8, TA around 80-120, and Borate near zero will be approximately correct. The further you go from those ranges the less these pH changes will correspond to reality.

With a pH of 6.8, that part at the bottom probably won't be accurate. Top area still is though. Also, if you did the first test with a TF-100, and the follow up pH test was done with a guess strip, I wouldn't trust that follow up result at all. Throw a dart at the forum wall and you'll hit a post with someone complaining their guess strips weren't accurate from one test to the next.

 

[JamesR]

I dunno. I will have him bring a sample to work with my kit and test it. My tf-100 does not do pH. We are using the 5 drops OTO in the plastic tester kit

 

[lightmaster]

I dunno. I will have him bring a sample to work with my kit and test it. My tf-100 does not do pH. We are using the 5 drops OTO in the plastic tester kit

Should have a blue box that says K-1000 on it in your TF-100 Kit.

 

[JamesR]

Yes, that k-1000 is the kit I use