Calcium Build up on Plaster - How to remove

[lardo5150]

I have quartzscape barbadous blue. All should be in my signature.
I will be honest, I let my CH testing lapse this winter. My fault. Won't do it again.
Tested today.
PH 7.5
FC 6
AK 50
CH 275

But I am noticing a TON of what I am guessing is calcium leaching on my plaster. Looks like tiny small dots of snow. Its all over my plaster, walls, floor, etc.

Is the only way to remove this is to drain and acid wash (which I know everyone discourages).

 

[ajw22]

Sounds like scale. Does it feel rough like sandpaper to your hand?

Post a complete set of test results including water temperature and CSI.

If you keep your water at an aggressive CSI between -0.3 to -0.6 for a few months it may dissolve the scale.

 

[lardo5150]

ok, I will work on it tomorrow and grab the gopro so you can see it also.

 

[lardo5150]

Sorry, just now did this.

Ok, here are my test results, after adjusting the CH the other day.

FC 5.5
PH 7.4
TA 50
CYA 40
CH 350 (this was 275 on Friday)
Salt 1800 (I am due to add more salt before spring looks like)
temp 55

My CSI was reading -.74
I am assuming this is not good. Now, I left Borates blank, I do not know how to test for that.
I am an idiot with math, in negative world, is -.74 less than -.6 (I can't add in my head but I can do code, which is weird, lol).

Anyways, what do you think? I will post pics shortly.
The CYA, I have never been able to get this right, even after buying the test sample.

Best place to get salt?

 

[ajw22]

-0.74 is less then -0.6.

Your CSI is low with your low water temperature because of your low pH. Let your pH rise a bit do CSI is around -0.5. That level of CSI aggressiveness can dissolve scale over a few months.

I like to use Mortons or Diamond Crystal pool salt. Never use Clorox Pool Salt as it is known to stain pools. I get it at Wal-Mart.

 

[lardo5150]

Where do I want the CSI to sit around normally? On the pool math app, it says anything lower than -.6 will cause damage.
The app says to keep it between -.6 and .6
So wouldn't -.74 be causing damage since it is lower than -.6

 

[Rancho Cost-a-Lotta]

Shoot for the range of 0 to -0.30 to avoid calcium scaling. I target a CSI of -0.20 to -0.30. With a relatively low TA of 50, you'll be in the range if you let your pH drift up to 8.0. You probably shouldn't allow your TA to drop any further. Every time you add MA, your TA will drop, so avoid aeration which leads to an increase in pH.

 

[ajw22]

The “damage” that a CSI below -0.6 can cause takes months to occur, not days or weeks. So it is a warning not to keep your CSI there normally. Excursions there for short periods of time don’t cause damage. It happens as water temperature and pH are changing.

In your case that “damage” is what will remove scale. So you want it for a few months.

You have not said if your pool surface has a rough sandpaper feel to it.

 

[ajw22]

Shoot for the range of 0 to -0.30 to avoid calcium scaling.

He suspects he has scaling. Running a lower CSI can help dissolve the scale.

 

[Rancho Cost-a-Lotta]

He suspects he has scaling. Running a lower CSI can help dissolve the scale.

Yes...didn't mean to add confusion to the situation.

 

[lardo5150]

Ok so to verify a few things...

Day to day, normal operation, I want to stay between -.2 and -.3 correct?

To see if I can get rid of the scaling, stay at this -.7 for the next month or so.

Does the site have any detail reading on how everything affects CSI, up and down?

At some point I am going to need to raise it back to -.2

EDIT: Reading CSI now in Pool School.

 

[lardo5150]

Ok, read through CSI on Pool School, and understand what it actually means now.

But there are no guidelines on how I can affect it one way or another.

 

[ajw22]

Ok so to verify a few things...

Day to day, normal operation, I want to stay between -.2 and -.3 correct?

Anywehere between 0 and -0.3 is fine. CSI will vary test to test due to changes in water temperature and pH. Don;t chase it, just keep it in that range.

To see if I can get rid of the scaling, stay at this -.7 for the next month or so.

You can keep it at -0.7 for a month. Then raise it to about -0.5 for another few months and see if the scale is getting smoother.

Does the site have any detail reading on how everything affects CSI, up and down?

Calcium Saturation Index (CSI)

How is CSI calculated? Very simple – use our PoolMath tool. To ensure long plaster life and save money, click here to learn more.

www.troublefreepool.com

CSI and LSI - Further Reading

www.troublefreepool.com

At some point I am going to need to raise it back to -.2

Yes, once you see the scale is dissolved or the lower CSI is not doing anything to it.

Ok, read through CSI on Pool School, and understand what it actually means now.

But there are no guidelines on how I can affect it one way or another.

You can see how CSI changes by playing "what if" with changes to chemicals in PoolMath

 

[JoyfulNoise]

Are you sure that’s scale? Is it rough and raised or does it feel smooth and level with the rest of the plaster. None of your test results posted shows a CH above 350ppm and your alkalinity is below 60ppm making your CSI negative. Scale will not form under those circumstances.

 

[lardo5150]

Are you sure that’s scale? Is it rough and raised or does it feel smooth and level with the rest of the plaster. None of your test results posted shows a CH above 350ppm and your alkalinity is below 60ppm making your CSI negative. Scale will not form under those circumstances.

Interesting.
Let me go feel it. I am still learning so this is all good helpful information, thanks!

 

[lardo5150]

my plaster was always "rough". The white spots are NOT raised.
I am just seeing more and more of them though, which is strange.
Can the plaster leach out calcium, without it being raised?

 

[ajw22]

my plaster was always "rough". The white spots are NOT raised.
I am just seeing more and more of them though, which is strange.
Can the plaster leach out calcium, without it being raised?

See if this fits what you have...

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

Diagnosing Pool Plaster Problems

Plaster Discolorations – New white pool plaster can discolor (darken or turn gray) from adding excessive calcium chloride set accelerator, from late hard troweling, from thin and thick areas due to an uneven shell, etc. Gray (or grey) mottled discoloration (also known as “water entrapment” or...

www.troublefreepool.com