How to remove milky white looking patches??

RyanN

Member
Jun 20, 2020
8
Arlington, Tx
Hello, I am new to the forum and a relatively new pool owner. We purchased the house a couple of years back and the previous owner had the pool refinished a couple of years before we bought it. I have been using liquid chlorine daily and shock when needed. The water stays clear but now I have these milky white patches that will not come off with scrubbing or shocking. It’s an in ground concrete pool. Thank you for the help in advance.
 

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RyanN

Member
Jun 20, 2020
8
Arlington, Tx
After reading a lot on here the past couple of days I am to blame for it. I was not keeping an eye on the ph and alkaline levels only going by the water being clear. I have began testing now and they were both really high. I have gotten them back down into range and now just trying to figure out how to get this out. I believe it is calcium silicate after doing some research.
 

RyanN

Member
Jun 20, 2020
8
Arlington, Tx
Welcome to the forum!
You say you use 'shock'. What is it and how do you apply it?
Does the plaster look 'bleached' out or are the patches rough feeling?
I suggest you read ABC's of Pool Water Chemistry.
A couple of the patches feel rough. I use hth pool shock but not on a regular schedule mainly when the algae begins to build up or we have a heavy rain. I read through the ABC’s of pool water chemistry and now understand the daily adding of the liquid chlorine raises the ph over time.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
30,945
Laughlin, NV
Liquid chlorine does not raise pH. pH naturally rises due to aeration and outgassing of carbon dioxide.

I doubt it is calcium silicate. But the HTH 'shock' I suspect is cal hypo. So it can create scale where it lands in the pool, especially if your TA and pH were high.

Do you have a proper test kit? Post up your test results.
 

RyanN

Member
Jun 20, 2020
8
Arlington, Tx
I have a deluxe dpd test kit from Leslie’s pools that came with the house. The highest reading for ph is 8.2 and it was darker than that, the alkaline took 10 drops of acid before turning red so I believe 100 ppm and the chlorine was at 2 ppm before I had added any liquid chlorine that day. But now after adding dry acid I’m at 7.2ph, 80 am and 3 chl.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
30,945
Laughlin, NV
Dry acid is not great to use if you have to adjust your pH often. Muriatic acid is preferred.

CYA? You will want to get a FAS-DPD test kit for FC/CC.

A FC of 3 is the absolute minimum. See FC/CYA Chart
 

RyanN

Member
Jun 20, 2020
8
Arlington, Tx
Liquid chlorine does not raise pH. pH naturally rises due to aeration and outgassing of carbon dioxide.

I doubt it is calcium silicate. But the HTH 'shock' I suspect is cal hypo. So it can create scale where it lands in the pool, especially if your TA and pH were high.

Do you have a proper test kit? Post up your test results.
In those same area there are green algae patches that also will not scrub off and do not change with shock. The lady at the local pool store also mentioned calcium silicate and said the algae is trapped underneath it. She recommended Beautec and brushing it several time after the application but I have not tried that yet. She also said I would probably need to drain it this winter and acid wash it, which seems like that does some damage.
 

RyanN

Member
Jun 20, 2020
8
Arlington, Tx
Liquid chlorine does not raise pH. pH naturally rises due to aeration and outgassing of carbon dioxide.

I doubt it is calcium silicate. But the HTH 'shock' I suspect is cal hypo. So it can create scale where it lands in the pool, especially if your TA and pH were high.

Do you have a proper test kit? Post up your test results.
What type of shock do you use/recommend?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
30,945
Laughlin, NV
Liquid chlorine should be used to chlorinate your pool water if you do not have a SaltWater Chlorine Generator to create it for you.
 

RyanN

Member
Jun 20, 2020
8
Arlington, Tx
When do you guys test your water? I use liquid chlorine and I’m trying to get an idea of how much it will need typically. Do I test in the morning before adding or after I have added and it ran? Thank you.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
30,945
Laughlin, NV
You test the FC of the water and then add enough chlorine to raise the FC up to the target range for your CYA. What time of day is up to you. Just be sure the pump runs for at least 30 minutes after adding the chlorine.