White Crystals in Pool

[Bart]

I just had my opened last week and there are white crystals growing on every surface that was under water during the winter. The sides, the walls,  and even the thermometer are coated with hard white crystals. The only surface that is still smooth is the step that was left out of the water when the pool was drained for the winter. 

Here is some more info:  it's a gunnite surface and a salt water pool. It was installed in the fall of 2010. We brushed it for 6 weeks or so then it was closed. We continued brushing it when it was opened in the spring of 2011 and for all of last year all surfaces were super smooth. We had it closed last fall by the pool company and opened by them as well. 

The crystals don't come off when I brush them but I was able to scrape some off with my finger nails. 

Here are the numbers:

FC - 0 (zero!) (I just turned the SWG on today)
CC - 0 (zero)
Ph - 8.2 (I fought to keep it down all last year)
TA - 120
CH - 600-700! (the test sample never really turned a blue color. It was very faint)
CYA - 55

Salinity 2.4


Does anyone have any idea what caused this and how to get rid of them?

I haven't called the pool company yet because I just got back into town and discovered this last night. 

Thanks!
Bart

 

[bobby1017]

Not an expert but with high ph & ch level I would assume it is scaling, lowering the ph would be a good first step.

 

[JasonLion]

That sounds rather like calcium scaling, and your test results are strongly suggestive of calcium scaling. However, calcium scaling isn't usually described as crystals. Do the crystals look anything like the ones in this topic? That kind of crystal results from a combination of high calcium and high sulfate levels. Sulfates can come from a variety of places, most commonly dry acid.

Regardless of what is happening, the first thing to do is to bring your PH down to around 7.2, as bobby1017 already suggested.

 

[Bart]

"Crystals" was probably the wrong word. It's more like bumps or roughness. It doesn't look like the photo in the linked thread. I took a water sample to my local pool store for testing and one of the guys said it was scale. The other guy didn't know what it was (which was slightly troubling!).

Here are the pool store test results:

Saturation Index - .9
CYA - 40
Total Cholrine - .5
Free Chlor - .5
pH - 8.2
Total Alk - 135
Total Alk adjusted - 123
Total Hardness - 200

Here's photo of the "crystals"/scale on the thermometer:

 

[Bart]

Sorry the photo is not that great.

Also, I forgot to metion that the polaris bag was full of this stuff after running a couple of hours.

I lowered the pH to 7.2 with 3 gallons of acid.

If it is scale, is there something I can get to help remove it? THe pool guy said they had to order some of the "scale remover" as they didn't have any in stock. Does that stuff work or is it just something to sell to people like me?!?!

 

[JasonLion]

If the scale is new you can sometimes get it to come off by lowering the PH to around 7.0 to 7.2 and adding sequestrant. Other times, especially if it has been around for a while, you need to either do an acid wash or manually scrape it off.

 

[Bart]

Thanks Jason!

Does the fact that the scale appeared this year (the second year of the pool's life) and didn't appear last year when we opened it suggest the pool company didn't put some inhibitor in during the closing?

 

[divepool]

Calcium and ph too high will cause this over the winter.