The Great Pool Plaster Workmanship vs. Water Balance Debate

[amarmels]

As they say on radio "Long time listener, first time caller."

I've spent hours reading many of the posts on this forum and they have been of tremendous help to me. Everything from the simple conversations regarding basic pool chemistry to the months long conversations and experiments regarding the affects of aeration and borates, and the interplay of CYA in chlorine effectiveness. Truly an impressive community. I've never posted because, quite simply, I've had nothing of value to add.

Now however, I find myself confronting what appears to be a hot topic in the pool industry, specifically, the finish in my brand new pool does not look correct, and I am trying to determine if it is a case of what member onBalance describes as "Plaster Discoloration" caused by the addition of "excessive calcium chloride set accelerator, from late hard troweling" or simply, as the pool contractor, would have me believe, the natural appearance of the material. In other words...HELP!

They say a picture is a worth a thousand words, so here is a photo that is a good representation of the mottled appearance of the pool.

The finish is made by CL Industries. It is their Hydrazzo product and the color is Gulfstream Blue mixed with 100% Platino, which should make for a blue-ish grey finish. In some spots this appears to be the case. In others, the finish is a much darker grey, tending toward black, and in other spots much lighter. In fact, because the differences are so pronounced and are spread across the entire finish, I can't even tell you which of the light, mid, dark colors the finish is supposed to be.

A few relevant details:

1) The pool finish was installed in late July, which, here in Jacksonville Florida, means it was HOT.
2) I was on vacation with my family and so I do not know if rain followed immediately after it was finished, or when the contractor started to fill the pool with water (two things I believe, based on my readings, that could cause problems).
3) The chemistry of the pool, which was the responsibility of the pool builder (not the plaster sub-contractor) to maintain, was not maintained. In particular, the pH was consistently above 8.0 during the weeks following the installation.
4) There was a great deal of plaster dust raised whenever the pool was brushed.
5) A few months after the initial installation, the pool was drained, and the finish scrubbed and acid washed by the pool plaster contractor in an effort to reduce or eliminate the uneven finish. I watched this work being performed and was amazed at the amount of dust removed. One could take one's hand and simply rub it along the plaster and rewove large swaths of darkened areas. It was reminiscent of wiping mildew off tile.
6) The pool surface looked better for a few days, but the mottling soon re-appeared.
7) The chemistry was now to be maintained by the finish sub-contractor (as he blamed th pool GC for not doing it right the first time.
8) It wasn't maintained well.
9) The mottling got worse
10) Here we are nine months later...

I've read as much as seems available on the topic, including on this forum and other places:

http://www.troublefreepool.com/threads/50222-Diagnosing-Pool-Plaster-Problems
http://www.troublefreepool.com/threads/41414-Ten-Guidelines-for-Quality-Pool-Plaster
http://www.troublefreepool.com/threads/15442-Problems-With-New-Diamond-Brite-plastered-Pool
http://www.troublefreepool.com/threads/15442-Problems-With-New-Diamond-Brite-plastered-Pool/page2
http://www.poolgeniusnetwork.com/profiles/blogs/gray-mottling-discoloration-of
http://www.poolgeniusnetwork.com/profiles/blogs/white-spotting-in-new-plaster-pools
http://www.poolgeniusnetwork.com/profiles/blog/list?user=2cpgio807ei8z&page=2
http://www.poolgeniusnetwork.com/profiles/blogs/npcs-decree-on-the-saturation
http://poolchloraz.com/links/

and much of it seems to specifically talk about white plaster. I think mine falls into a similar category, as the Hydrozzo product is, per the manufacturer "blended marble aggregate, white Portland cement, graded color aggregate and proprietary ingredients," but would love to know for certain.

A last few details about the pools chemistry:

1) All but impossible to keep the pH below 8.0. Over 10 gallons of Muriatic acid added during March to a 30,000 gallon pool and the pH still spends most of its time between 7.6 and 8.0+
2) Calcium levels are always at 600ppm, which seems awfully high
3) On a possibly related bot, lots of scale on the tile of the outer edge of the vanishing edge and the spillover part of the spa.
4) Alkalinity kept around 75, as the saturation index, due to the pH and Calcium tends to be quite high, especially as the temperature is now rising (at pH 8.0 sat index is approaching 0.9 and will only get worse as the pool warms)
5) No problem with chlorine as I modify output of SWCG to keep it at around 3.0. CYA is 30, but I will raise as summer approaches.

So, the million, or at least few thousand dollar question is, "Is my pool finish appearance the result of poor workmanship, water balance, both, or neither? Any insights are greatly appreciated, and thank you for listening.

----20x40 30,000 gallon plaster, in-ground pool with attached spa, vanishing edge and waterfall, in-floor cleaner, 3 pumps, 3 filters, SWCG, Jandy Aqualink, some lights, switches, valves and gizmos that may or may not do anything, but will certainly break immediately following the end of the warranty period.

 

[JasonLion]

The water balance certainly sounds problematic. Your current conditions will be very prone to scaling, which will slowly and unevenly tint the surface white rather than blue.

The high CH level is probably due to adding too much acid at one time, although there could be other causes. Have you tested your fill water CH level?

It is very difficult to keep PH stable in a vanishing edge pool if the edge waterfall is used much at all. The closest you can come is by using borates and lowering TA to around 40, but even then a vanishing edge will usually drive the PH up at least slowly. A vanishing edge with TA around 75 will certainly drive the PH up very quickly, which is problematic with CH at 600.

Hydrazzo finishes are sensitive to proper water balance, at least as much as plain plaster and usually more so.

There is not really enough information here to comment on workmanship during the original plastering and the subsequent acid wash. You mentioned that the surface look good after the acid washed by the pool plaster contractor, so that at least suggests good work, but really there isn't enough there to comment on.

Situations like these definitely require careful and consistent management of the PH. You haven't really said much that addresses that, but the general tone and the chemical readings both suggest that PH has gone out of bounds both low and high. If that has indeed happened with some regularity, it is sufficient to explain all of the issues you have mentioned. That doesn't mean there aren't other issues, but PH regulation does look like the most likely candidate for a primary cause.

 

[amarmels]

The water balance certainly sounds problematic. Your current conditions will be very prone to scaling, which will slowly and unevenly tint the surface white rather than blue.

The high CH level is probably due to adding too much acid at one time, although there could be other causes. Have you tested your fill water CH level?

It is very difficult to keep PH stable in a vanishing edge pool if the edge waterfall is used much at all. The closest you can come is by using borates and lowering TA to around 40, but even then a vanishing edge will usually drive the PH up at least slowly. A vanishing edge with TA around 75 will certainly drive the PH up very quickly, which is problematic with CH at 600.

Hydrazzo finishes are sensitive to proper water balance, at least as much as plain plaster and usually more so.

There is not really enough information here to comment on workmanship during the original plastering and the subsequent acid wash. You mentioned that the surface look good after the acid washed by the pool plaster contractor, so that at least suggests good work, but really there isn't enough there to comment on.

Situations like these definitely require careful and consistent management of the PH. You haven't really said much that addresses that, but the general tone and the chemical readings both suggest that PH has gone out of bounds both low and high. If that has indeed happened with some regularity, it is sufficient to explain all of the issues you have mentioned. That doesn't mean there aren't other issues, but PH regulation does look like the most likely candidate for a primary cause.

JasonLion,

Thank you for your reply. A couple of follow-up thoughts, questions and answers to your questions:

1) In response to the question about the CH of the fill water, it is 150ppm. One of the things I have wondered is how it got so high. My primary suspect is the calcium chloride that leached out of the plaster during the curing process. If so, could this be a case of too much calcium chloride during the laying of the plaster or too high of a water to cement ratio which led to a greater release of calcium hydroxide, or both?

2) Sorry, but I don't follow you at all regarding how adding Muriatic Acid can raise the CH and can't seem to locate information on the connection between the two. Would you please elaborate? Also, for what it is worth, the CH has been 600 for months, despite the addition of 20 or more gallons of MA.

3) I understand from other posts that aerating the pool can be used to lower the alkalinity, but first the pH must be lowered to 7.0 - 7.2. The suggested way to do this Muriatic Acid. If I add enough to lower the pH to the suggested level, will I be raising the CH as mentioned in #2?

4) Will keeping the TA at 40 cause the pH to swing around as just about every publication says it will? I imagine the borates will help, but am I replacing one problem with another?

5) I do run the vanishing edge for a couple of hours every day. It is about 20' long and the drop is approximately 8'. Even though I run the pump only hard enough to have the water trickle over the side, I hadn't really considered this as a possible part of the climbing pH, but now that you mention it... I can certainly decrease the amount of time for which the VE is run, but as the trough it empties into is about 2,200 gallons, and sits in the sun most of day, I want to make certain it circulates enough to avoid any problems. Any thoughts on minimum time or just good-old trial and error?

6) Lastly, what do you make of the finish as shown in the photos? Normal terrazzo look? Something amiss?

So, how's about this as a plan of attack:

1) Drain the pool (gets rid of the water that has a CH of 600 and replaces it with some around 150ppm)
2) Acid wash it (should eliminate the scale and hopefully much of the mottled surface)
3) Fill the pool (guess why is kinda obvious)
4) Take some baseline readings
5) Add salt and CYA
6) Lower Alkalinity to 45 using the method described on this forum ("Lower Total Alkalinity" Published on 01-18-2014)
7) Buy Muriatic Acid in 55 gallon drums and use as necessary to keep pH in range
8) Add Borates as described in this forum while trying like mad to keep the pH down
9) Minimize use of vanishing edge

Thanks again for you help.

 

[JasonLion]

1) With CH in your fill water, the CH level will go up over time. CH doesn't evaporate, and every time you add water you are adding more CH. It is also completely normal for fresh plaster to raise the CH level by 200 to 300 over the starting level as it cures during the first month, and a little more over the first year, before it eventually stops.

2) If you add too much acid at one time the PH will go down enough to leach calcium out of the plaster (and into the water). The is really a function of low PH, not acid as such. But adding acid is really the only way the PH could get low.

3) No, not in your situation. Just don't lower the PH below 7.0.

4) Adding borates provides a separate PH buffer that allows you to lower TA further without having problems like that. Without borates lowering TA that low could cause trouble.

5) Half an hour to an hour is plenty to run the VE each day.

6) The photos are difficult to evaluate. The visible color variation is higher than what I would expect, but some of that might have to do with lighting rather than actual color variation, so I can't be sure. Calcium scaling tends to be less uniform/patchy, so the photos mostly argue against that interpretation, but don't rule it out.

Your plan is mostly reasonable, though I wouldn't replace 100% of the water, probably 60% to 70%, and add borates before lowering TA below 60. Also, I doubt you will really need a 55 gallon drum of acid, though perhaps a 15 gallon drum would be worth getting if you can find it.

 

[onBalance]

The following is my take on probable causes of blotchy discoloration of the above colored pool plaster. Unfortunately, the pictures do not provide sufficient clarity as to the severity of the discoloration patterns of whether it is normal or abnormal.

1. If an "inorganic" color pigment was added to the plaster mix, including calcium chloride (accelerator), that can cause a whitish blotchy discoloration appearance over time.
2. If an "organic" color pigment was added which is especially problematic, this can bleach out (and create a blotchy appearance) due to the presence of chlorine in the water.
3. Adding water while troweling may cause a blotchy or streaky appearance over time. This is due to increased porosity (of defective areas on the surface) which naturally breaks down (continued leaching) in balanced pool water.
4. An acid wash may create a "uniform color" of the plaster at first, but over time the color may likely turn whitish again and create a blotchy appearance.
5. An acid wash can cause more etching of the plaster in certain areas as opposed to other areas, hence, a mottled appearance over time due to continue deterioration.
6. Calcium scaling is more likely to be uniform, unless the quality of the plaster surface is not uniform.
7. A porous and etched plaster surface can more easily attract calcium scaling deposits.
8. Aggressive water causes uniform etching, unless the quality of the plaster surface is not uniform. (This has to do with the quality of materials and workmanship).
9. Another acid wash will make matters worse. It will make the plaster color darker and uniform again, but the whitening will likely return again.
10. It is not normal for the calcium level to increase 400 ppm in a new pool.
11. The increase in the calcium level is likely do to two issues. Poor quality pool plaster, including an excessive amount of calcium chloride and high water/cement ratio, and aggressive water.
12. A defective plaster surface can slowly deteriorate and cause blotchy discoloration over time.
13. Proper plastering practices, followed by proper start-up and continued water balancing, will prevent any calcium (CH) from leaving a "curing" plaster finish and increasing the CH of the pool water.

 

[amarmels]

Much thanks to JasonLion and OnBalance.

JasonLion: I really appreciate the line by line response to my plan. I'll definitely follow your instructions on how to handle the chemistry as I move forward. BTW, I was kidding about the 55 gallon drum

OnBalance, you have really has nailed my concern on the head (which isn't surprising because most of what I know of this phenomenon is from your work, especially your work posted on poolhelp and your blog at poolgeniusnetwork). The concern is this: if my problem is as you suspect, the increased porosity not only makes the finish look bad, but far worse, significantly shortens the life expectancy of the pool, and the only remedy you've mentioned in your work is to have the is to have the pool re-plastered.

As you can imagine, if I am going to go down this road with the pool builder, I'd like to know as much about the issue as possible. I'd really like to speak with you about it further offline. Is this possible?

Thank you again.