What is happening to my plaster?

[new-to-poolcare]

Now that I have taken Step #1: "practice with your testing, trust your numbers, forget about the pool store, trust TFP", I would like to know if I have a real problem with the pool surface. Although the water continues to look clear, I see what looks like dirt but it won't brush off.





FC: 4
CC: 0
CYA: 95
PH: 7.9
TA: 160
CH: 760
I use 12.5% Sodium Hypochlorite and 20° Baume 31.45% Hydrogen Chloride.

It is much more noticeable with no sunlight but not as bad as the pictures seem to show. Is this a problem I can deal with? Thank you.

 

[Texas Splash]

We'll try to help you figure out what that staining is. Here's a quick way to test for the obvious items:
- Chlorine tab/puck rubbed on the area for a minute or two = organic (algae staining)
- Vitamin C tabs crushed in a thin sock or nylon = iron
- If the Vitamin C tabs made the staining darker/worse, try dry acid = copper

Last but not least, hard water is fairly common in your region. Your CH, TA and pH are all elevated. It's possible that is calcium scale staining. Does it feel rough? If the items above don't work and you ever lower the water level to expose that first step, try brushing/scrapping some of that stained residue off (if possible), place in a pile and add some muriatic acid on it to see if it fizzles.

You definitely want the pH much lower right now since your CH is elevated. I'd keep the pH down to about 7.2-7.4 for a while. That should also help lower the TA which is a bit elevated. Not much you can do about the high CH until you are ready to exchange water. But that may be coming soon as well since your CYA is very high. Somehow stabilizer has been introduced to the water causing it to get that high. Just like CH, the only way to lower CYA is by water exchange.

Here's a thought - I suspect you will need to exchange some water. When the water level drops (to lower CYA and CH) and exposes the step, try to obtain some of that stuff like I noted above and do the acid test to see if there's a reaction. Certainly your call based on water restrictions (if any) in your area, but the CYA and CH are high. A good water exchange of about 40-50% should help with those two items. Try those test above as well and let us know how it goes.

 

[duraleigh]

It looks like you have calcium scale. Your pH and CH have both been too high for an extended period.

Test the CH and pH of your fill water and post that up. Be prepared to drain and refill about 50% of your pool because your CYA is too high as well.

Getting rid of scale is not easy but post up the fill water results and we'll get started on it.

 

[Jimrahbe]

new,

How old is the plaster??

Thanks,

Jim R.

 

[new-to-poolcare]

How old is the plaster??

I am looking into that for an answer.

 

[new-to-poolcare]

Chlorine tab/puck rubbed on the area for a minute or two = organic (algae staining)

I think the abrasive nature of the tab removed some of the stain but otherwise no change.

Vitamin C tabs crushed in a thin sock or nylon = iron

No change.

Does it feel rough?

I forgot to check but it looks a little rough in some areas.

You definitely want the pH much lower right now since your CH is elevated.

I have been adding muriatic acid weekly to try to lower TA and pH.

 

[mknauss]

Test your pH every other day. You may find it is rising back to 7.8+ very quickly with that high TA.

 

[new-to-poolcare]

Test the CH and pH of your fill water and post that up.

Oops, I only tested the TA of fill water: 110.
I will check CH and pH ASAP.

- - - Updated - - -

How old is the plaster??

20+ years.

 

[new-to-poolcare]

Test your pH every other day.

Thank you. I will.

 

[new-to-poolcare]

Test the CH and pH of your fill water and post that up.

CH: 150; pH: 7.5

 

[mknauss]

It is about time to plan on a water exchange with a re-plaster!

Pretty sure your 'stains' are dirty calcium scale. Not much you can do about it but re-plaster sometime in the future.