Calcium delight: combination of surface staining and nodules

3rdcoaster

Silver Supporter
Apr 28, 2018
23
Houston TX
My pool surface has always had white chalky staining, so much of it that it wasn't clear what the true quartz french grey color was supposed to look like for the first 2 years of ownership. The pool was put in as part of a new home build, and there were too many issues to deal with in parallel to figure out what was going on. Both the home builder and the pool subcontractor were absolutely "see no evil" silent on this, telling me that it was "a natural material" and variation was expected. I gradually learned more and realized I'd signed a "builder has no liability" (to summarize) contract on the pool. YOYO.

The hazy, patchy staining has gradually improved with careful management of the CSI. A big improvement came with installation of intelliPH in year 3, which delivers small doses of acid all day as the chlorine generator runs. Otherwise in summer when water is in the 80s for months, and evaporation increases pool Ca, pH can rise significantly during the day. I now can see the actual quartz color coming into view, in patches of the floor and walls, between the stains. So I know what direction I need to go.

However, beginning maybe 6 mo after build, what I now know are Ca nodules began to appear. They are small thin teardrops/icicles, always white, and easily scraped off with a fingernail when smaller or with a putty knife if allowed to get bigger. There are small white patches on the pool floor.

I know I have a less-than-perfect install; there are good TFP threads about what is a Ca nodule and this video (
) has a good explanation and includes examples of core sampling of the pool wall. I know a combination of acid and scrubbing works, I've cleaned off a few areas on some plastered steps, but its slow and labor intensive. What I'm worried about is that a whole pool acid wash might open up the nodules (bad) while clearing the surface staining (good). I'm caught between the rocks (nodules) and the hard places (surface stain)! Has anyone tried the treatment offered by poolstainremoversdotcom? Is it safer than acid and effective? Other suggestions welcome.
Ed
 

3rdcoaster

Silver Supporter
Apr 28, 2018
23
Houston TX
OK here are current chem stats and a couple pics, although i find it hard to photograph well without a manual focus...
pH 7.3 lowered a bit for current campaign, usually runs 7.5-7.6
Ca 375
NaCl 2900 (its been raining)
Alk 80
Cya 70
Cl 4
CSI =-0.41

first is a couple years ago when i did a partial drain to lower Ca, which was 550 or so...currently the nodules are scraped off with a putty knife, shows both nodules and surface mottling.
2nd is a current, night shot, mottling is improved now but still present.

Welcome any alt diagnoses or suggestions for best approach to continued remediation.

Thanks!
Ed

nodules-partial drain.jpgfloor2.jpg
 
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onBalance

TFP Expert
LifeTime Supporter
In The Industry
Jul 25, 2011
1,218
Utah
Sorry that there hasn't been any recent responses to your last post.
The situation here is that the pool plaster is mottled, but the more serious problem is that the plaster has a bonding problem and the white calcium nodules and cracks are the visible result.

I suggest you contact the builder and ask for a re-plaster. It should be covered under warranty. That is really the only and proper remedy. Nothing can reverse the continual formation of nodules.

The following article will help explain this issue better than the video you posted above. Nodules are not caused by bad or improper water balance.

 
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3rdcoaster

Silver Supporter
Apr 28, 2018
23
Houston TX
OnB: thanks for your reply. I had read the Ca Nodules thread (and many others) and share the concern, but based on past PB responses and the language of the warranty (good topic for another thread: "what to look for and require in a PB contract!!") seems to favor the builder (IANAL), i.e. plaster is excluded, my focus is on diminishing visible staining.

In the meantime, I completed a treatment using a kit purchased online from the vendor listed above, who also provided helpful support.

I am reporting again on the outcome of my attempted treatment of my combination of Calcium leaching from startup, calcium staining, and nodules.

Treatment yielded a significant improvement in the staining (including the gravity-driven wall tracks of the nodules and apparent surface linear cracks). Each additional brushing effort clears the staining incrementally and clouds the water; with filtration, the water clears. My nylon wall whale doesn't do much, the stainless steel brush is effective.

My current pool chem is:
Here are readings Today (about day 38):
Ca: 800 (much increased from pre-treatment)
pH: 7.5
Alk: 45 (down from pre-treatment), much lower than normal
Chl: 3
Cya: didn't recheck
CSI: -0.29
NaCl 3350
Temp 88
I am using IC40 set at 25%, intellipH set at 100% (4 cc of 50% MA per hour), and running the single speed pump 9 hr/day. Water is clear (see photos)

questions are: I need to break down the adherent Ca, which I seem to be doing based on the clearing and the rising free Ca in the water. Do I just and maintain the current course including with more brushing? Or add alk to a normal level and slow things down, bringing CSI towards 0? Before raising Alk, should I drop the Ca by partial refill? How comfortable should I be with keeping the polyacrylamides in my swimming water (they are reportedly non-toxic, but may produce breakdown product acrylamide which might be toxic)?

Very grateful for additional feedback.IMG_0173.jpgIMG_0175.jpg
 

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onBalance

TFP Expert
LifeTime Supporter
In The Industry
Jul 25, 2011
1,218
Utah
IMO, the mottling will return and so will more calcium nodules, making what you are doing a continual and frustrating program. Check out Texas law on required warranties for workmanship and materials from contractors. Pushing hard with the contractor may work. This appears to be very poor workmanship.
 
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