stains and discoloration after new plaster

[statenine]

We recently had our pool re-plastered using Finest Finish white plaster. Once they told us the startup was complete and the pool was swimmable (about 4 weeks after construction was finished), we had a new pool cleaner start and he told us that he noticed what looks to be dirt in the bottom of the pool, but it is not coming off. He thinks it may be plaster dust that has adhered to the surface due to incorrect startup by the contractor. I had the contractor come out this morning to take a look and he said something was spilled in the pool and it is not due to incorrect staurtup, but I don't buy that. He took a water sample and said he is going to check it at his lab and get back to me, but he mentioned we may need to acid wash the pool. I've read on this forum that you should not acid wash new plaster though? Here are a couple pics, this is EVERYWHERE and not just in a small area. Any help in understanding what this is and what caused it would be greatly appreciated!

 

[woodyp]

I don't know...but here's a free thread bump!

 

[statenine]

Our contractor just emailed me back his water test results pointing his finger at our pool cleaner:

Chlorine: 0 ppm, 3pp is ideal

Ph: 8.0+ (cant measure further, it could be really high), 7.4 is ideal

Alkalinity: 160, 100 is ideal

Cynuric Acid (aka conditioner): 50, 30-50 is ideal (don’t use tabs, has too much cya)

Calcium: 450, Health Department says deal with it over 500ppm. We generally recommend no more than 750ppm

TDS: 970, under 1500 is ideal

Salt: 620, 0 is ideal but pool service cant control it anyway. Its not a major issue until around 3500

Langlier Saturation Index (LSI): .774. The ideal range is -.3 to +.3. He’s way off the chart. The water is scale forming and aggressive to the plaster.

We ended the 30 day startup at 280ppm calcium hardness. In three months it went up to 450. Given that there isn’t much make up water yet as the pools are not evaporating much so your calcium should maybe be 300ppm by now. A 170 increase is generally more than a year when left to its own. The only other place the water can get calcium is from the plaster. Aggressive water will attack the plaster and pull calcium out of it in an attempt to balance the water.

 

[Rollercoastr]

I'm confused by a few of his assertions. (I'm trying to ignore that a pool expert mis-spelled cyanuric and Langelier...)

He recorded an LSI/CSI of .774 That's positive, yet according to him, aggressive?? So he ended the startup with CH at 280. Now he measures 450 and claims the water is aggressive and has pulled additional calcium from the plaster.

Isn't it generally agreed that "aggressive" water has a negative LSI/CSI / low CH? I don't understand how he's claiming that he left the pool with CH where he wanted it, and now it's higher, so the water robbed the fresh plaster of that calcium, but it's someone else's fault...

 

[statenine]

Thank you for the reply. Do you have an idea as to what would have caused this staining in the photos? Is this most likely from incorrect startup techniques or is it due to chemical imbalance?

All I really need to find out is who is at fault...our contractor or our pool cleaner. Then I can go to that person requesting they pay to fix this. Are there pool/plaster inspectors that I can hire to come out and take a look and give me their thoughts on what the cause was?

Thanks!

 

[Rollercoastr]

I wish I could tell you what's going on. One could argue that a startup technique IS chemical balance, right? It's just adding/adjusting chemicals based on the fragile, curing state of the plaster...

I suppose the issues you're seeing could be due to a defect in the product or workmanship as it was being applied as well.

What I'm struggling with is what I see as a contradiction in the contractor's explanation, but maybe I'm mis-understanding something.

 

[statenine]

Ok thanks. Our pool cleaner told us he thought it was plaster dust that settled and adhered to the surface. And that is caused from not brushing it often enough or for long enough. Is that a possibility?

 

[skimmerswimmer]

I think someone needs to be brushing new plaster like 3 times a day for the first week or so. It's a lot of work and time and most of the work is to remove the extra "cream" that leaches from new plaster. The PH also needs to be kept low (7.0) during this period with lots of muriatic acid additions since it will rise quickly each day.

 

[Swampwoman]

Statenine, it’s tough to give guidance when it’s 3rd party on either side but I just want to say if those test results are accurate your pool service is not doing you any favors. Eg. Zero chlorine!

If you left the startup work in the hands of a pool service that would let your FC zero out, then in your shoes, my confidence level would not be high that they followed correct start up procedures. That doesn’t necessarily mean the staining wasn’t an installation related problem but it certainly doesn’t help your case.

For the future, I’m glad you’ve found TFP. Get a good fas/dpd test kit of your own at TFTestkits.net, read up in pool school, and take over your pool

I realize that doesn’t help your immediate concern. For disputes such as this you might want to consult with a professional assessor. There is a poster on this forum called OnBalance who is part of a company by the same name who I believe offer assessment in cases such as these. Maybe try to message On Balance.

 

[onBalance]

Please determine your tap (or fill) water readings for pH, alkalinity, and calcium hardness and post here.
Also, I suggest you have another testing of the pool water to verify if the tests results given you above are accurate, and let us know.
A couple more photos would be helpful of other discoloration areas.
Plaster dust is white, and can be easily sanded off. What I see is a darkening and blotchy patterns. And that type of discoloration doesn't easily sand off. Is that the case?
Use 100 grit wet and dry sandpaper.