Plaster Stains

[jacepool]

Hi all,
I am a new pool owner and new to TFP. My pool was just finished and I have been maintaining it 2 weeks now. The pool is 20 x 30 ft, 18,000 gallons, all Jandy equipment, salt water, plaster, with marble tile and travertine coping. I have been noticing stains recently (see attached) and they will not come off with regular scrubbing. Below are my recent test results. What should I do?

Ph = 7.9 (just added some muriatic acid to lower)
FC = +10 (to help lower I put the SWG on 0%)
TA = 70
CH = 290
CYA = 95
Salt = 2700

 

[Bperry]

Hi all,
I am a new pool owner and new to TFP. My pool was just finished and I have been maintaining it 2 weeks now. The pool is 20 x 30 ft, 18,000 gallons, all Jandy equipment, salt water, plaster, with marble tile and travertine coping. I have been noticing stains recently (see attached) and they will not come off with regular scrubbing. Below are my recent test results. What should I do?

Ph = 7.9 (just added some muriatic acid to lower)
FC = +10 (to help lower I put the SWG on 0%)
TA = 70
CH = 290
CYA = 95
Salt = 2700

How are you testing the water? Are the stains your talking about the dark spots or the white streaky areas?

 

[ajw22]

Welcome to TFP.

You should not have added salt or ran your SWG for the first 30 days. And your FC is too high while the plaster is curing. The high chlorine can bleach the color out of new plaster. Plaster startup guides recommend you keep the FC below 3ppm for the first 30 days.

When Should Salt be Added?

In our industry, there seems to be some consensus to wait 30 days before adding salt to new plaster pools, yet some say it is okay to add salt within a couple of days of filling the pool. So who is right? To answer that question, let’s first take a look first at what happens in the initial...

www.troublefreepool.com

That looks like typical mottling and white spotting that happens on dark colored plaster. Maybe compounded by the poor startup with the salt added and high FC.

We do not recommend that you do an acid wash to remediate the problem which is what your pool builder will suggest. An acid wash will take a few years of life off of your plaster.

White Spotting of New Plaster Pools

The problem of plaster spotting has been an ongoing puzzle and controversy in the swimming pool industry for over three decades. The generally round, smooth-yet-unsightly white soft spots in new plaster pools have long been a source of contention among pool plasterers, and pool chemical service...

www.troublefreepool.com

Plaster Installation and Maintenance - Further Reading

www.troublefreepool.com

 

[jacepool]

How are you testing the water? Are the stains your talking about the dark spots or the white streaky areas?

I am referring to the dark spots. There are a few others in the pool also. I use a Taylor K-2005 Test Kit to test the water.

 

[jacepool]

Welcome to TFP.

You should not have added salt or ran your SWG for the first 30 days. And your FC is too high while the plaster is curing. The high chlorine can bleach the color out of new plaster. Plaster startup guides recommend you keep the FC below 3ppm for the first 30 days.

When Should Salt be Added?

In our industry, there seems to be some consensus to wait 30 days before adding salt to new plaster pools, yet some say it is okay to add salt within a couple of days of filling the pool. So who is right? To answer that question, let’s first take a look first at what happens in the initial...

www.troublefreepool.com

That looks like typical mottling and white spotting that happens on dark colored plaster. Maybe compounded by the poor startup with the salt added and high FC.

We do not recommend that you do an acid wash to remediate the problem which is what your pool builder will suggest. An acid wash will take a few years of life off of your plaster.

White Spotting of New Plaster Pools

The problem of plaster spotting has been an ongoing puzzle and controversy in the swimming pool industry for over three decades. The generally round, smooth-yet-unsightly white soft spots in new plaster pools have long been a source of contention among pool plasterers, and pool chemical service...

www.troublefreepool.com

Plaster Installation and Maintenance - Further Reading

www.troublefreepool.com

Thanks. The pool was filled in late ~October / early November and the builder waited about 2 weeks before adding salt. Do you know what the dark spots could be? My pool builder told me the white spotting would fade away with time.

 

[ajw22]

Thanks. The pool was filled in late ~October / early November and the builder waited about 2 weeks before adding salt.

Sounds like your builder had a different startup process then most.

Do you know what the dark spots could be?

Variations in the plaster color mix.

Sand some dark spots with 80/100 grit wet/dry sandpaper and see what color is exposed.

My pool builder told me the white spotting would fade away with time.

Sure, anything white gets dirty and fades outdoors.

 

[Bperry]

I am referring to the dark spots. There are a few others in the pool also. I use a Taylor K-2005 Test Kit to test the water.

With a CYA of 95 (TFP always rounds up to nearest decade) your FC can be up to 13ppm so it’s not that far out of whack, though the pH test gets wonky after 10ppm FC so maybe don’t trust that one too much. I can’t speak to the plaster startup issue.

I thought the Taylor K-2005 couldn’t measure FC above 5ppm? You might consider getting the FAS-DPD portion to make the kit into a K2006 (which is what TFP recommends) and you’ll get more accurate chlorine readings.

Can you scrape any of the spots up on a paper towel or rub a tricolor tablet on it to see how it reacts? Maybe don’t do the tablet yet if you have new plaster.

 

[jacepool]

With a CYA of 95 (TFP always rounds up to nearest decade) your FC can be up to 13ppm so it’s not that far out of whack, though the pH test gets wonky after 10ppm FC so maybe don’t trust that one too much. I can’t speak to the plaster startup issue.

I thought the Taylor K-2005 couldn’t measure FC above 5ppm? You might consider getting the FAS-DPD portion to make the kit into a K2006 (which is what TFP recommends) and you’ll get more accurate chlorine readings.

Can you scrape any of the spots up on a paper towel or rub a tricolor tablet on it to see how it reacts? Maybe don’t do the tablet yet if you have new plaster.

I will try this after a few weeks to let the plaster settle some more. For the FC, I have a SWG and TFP mentions a target of 7. With the chlorine being so high is that of any concern?

 

[Bperry]

I will try this after a few weeks to let the plaster settle some more. For the FC, I have a SWG and TFP mentions a target of 7. With the chlorine being so high is that of any concern?

The target is what you shoot for on a daily basis kind of like an average. It’s safe from five all the way up to 13 if your CYA is so high.
But those numbers are for cured plaster. If you’re plaster is new, the FC is evidently recommended to be under 3ppm.