Ph is purple

Kelli2

Well-known member
May 26, 2020
58
Pennsylvania
Pool Size
4500
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
Just opened pool yesterday and ph is purple! I get no result when I check FC, no color change, but my husband dumped a gallon of bleach in the pool when we opened it (it was totally green). Pool is 18x9 Intex above ground with SWG and sand pump (4500 gal). Not sure where to go from here since I can’t get a ph reading and need to adjust that before doing anything else.
 
Sounds like your CYA might have been converted to ammonia over the winter. I know it sounds counter-intuitive but if that is the case then you'll want to take care of that and then the pH because the reaction is acidic and you might overshoot if you do the pH adjustment first.

While the pump is running you'll want to add 10 ppm worth of chlorine (about a quart of 10%), let it mix for 10-15 minutes, and check the FC again. If it is below 5 ppm then bring the FC back to 10 ppm and repeat the process. When your water can hold over 5 ppm then you can retest the pH and hopefully will get a readable test.

If your pH is still off the chart (and your FC is below 10 ppm) then treat it like 8 and add enough acid to lower the pH from 8 to 7.2. Let that mix for at least 30 minutes and retest. Repeat as necessary.

Once all that's done you can add CYA and begin the SLAM Process proper.
 
Thank you for that! I forgot to mention that I did treat the ph last night as if the ph was 8 and added the 2 oz of muriatic acid and nothing changed this morning. Should I do it again?
 
Thank you for that! I forgot to mention that I did treat the ph last night as if the ph was 8 and added the 2 oz of muriatic acid and nothing changed this morning. Should I do it again?
Yes.

Repeat the acid additions until the pH is into the 7's.

What is your TA?
 
Purple is too subjective.

Post a pic of the Ph test and also a pic of using 4 drops instead of 5.
 
What chlorine test are you using?

Is your pump running?

Stop adding acid and let your water circulate for a few days.

Whatever your pH is, it will not hurt anything.

If your pH is not looking normal tomorrow, then post a picture of it against a white background.
 

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This is with 4 drops instead of 5. Pump has been running since yesterday morning when I opened. FC will only hold at 5 for a a couple hours so I know I need to SLAM but thought I needed ph at 7.2 before doing that. Also I see I forgot to post CYA which is 0.
 

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The FAs/DPD chlorine test using powder that turns the sample pink and then drops until it turns clear?

What sample size are you using and how many drops is the test taking?
 
The FAs/DPD chlorine test using powder that turns the sample pink and then drops until it turns clear?

What sample size are you using and how many drops is the test taking?
Yes, that’s the one. I do the 25ml sample, and it takes 9 drops to turn clear. I fully expected that result since I had full blooming algae when I opened.
 
Sounds like your FC is fine.

Keep adding small amounts of acid and test both your pH and TA.
 
Unfortunately the FC drops after an hour, it’s already down to 3 again. I suppose I should focus on the ph first?
Add CYA to CYA 30. CYA is a mild acid and will lower pH a bit anyway.

Once you add the stabilizer accept the pH you have and begin the SLAM.

Deal with the pH after you clear the pool up.
 

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