Low calcium levels, plasticizers in vinyl liners, leaching cobalt from fibergalss?

[waterbear]

I've heard things like this, but when I've had the opportunity to ask engineers with one of the two big manufacturers of vinyl sheet, they were very skeptical and doubtful.

But . . . I'd be very grateful if you'd mail, scan and email, or fax me copies of this info. I'd love to read it carefully. If you can, PM me and let me know how you can send it, and I'll give you the info you need.

Thanks!

Ben

Will be glad to fax it to you. I just want to restate that it was the gentlman from Ace Hardware that told me that WaterTEQ has done this research. The exact quote concerning calcium is:

"Water has an appetite for metals and minerals that will be satisfied. If it's appetite is not satisfied, it will pull the calcium out of plaster or marcite, gunite, or shotcrete pools, and the plastecisers out of vinyl liner pools, and the cobalt out of fiberglass finishes. Low calcium hardness will cause deterioration fo these finishes and shorten the life of the pool or spa surface."

Like I said in my original post the handout was one on general water chemistry and it was all sound information. That is why I questioned this one statement since no references were given. The only thing I have been able to find to support this is in the maintenance manual for San Juan fiberglass pools and in the Pool Care guide from Royal fiberglass pools and once again, no refereces to any research have been given.

I could find NOTHING to support the claim for vinyl liners!
I own a San Juan pool so you can understand my concern to find the truth out!

Edit: Update, my builder was out today to try and get the rest of the fiber optics running and I asked him about this. His feeling (and he builds both fiberglass and gunite) is that you don't have to worry about calcium in a fiberglass pool. I showed him the San Juan manual that I downloaded (funny that he never gave me a hard copy one ) and he said he would check with San Juan about it becuase it goes against everything that he knows. As soon (or if, which is more likely with him) he gets back to me I will post the info on here.

[mwsmith2]

Amazingly enough, I was just about to start a new thread when I saw this one. My basic premise is this:

All pools need some calcium



Now my above conclusion is based on the the Langelier Saturation index. I suppose the real question is, do you believe in the SI or not? If you don't, then I essentially don't have much basis for my conclusion. If you do believe in it, then my argument may have some merit.

Now, I don't know for sure if I'm right or not, that's why I'm hoping I'll get some input on this thread. I'm sure someone will join in.

Here's the deal. With the SI, you want to keep your water "balanced". That is to say, not in a corrosive condition, and not in a scaling condition. I was answering some questions today on here, and ran a few scenarios through the SI calculator found here:

http://www.csgnetwork.com/langeliersicalc.html

Basically what I found is that if you have a normal pool, which is:

Temp 82
Alk 125
pH 7.6


You can't stay out of a corrosive condition without some calcium in your water. Now it doesn't take much to get out of that corrosive condition, 125 ppm seems to do the trick. The other interesting thing is that with the above pool example, even having sky-high calcium, doesn't put you in a severe scaling condition. It is also true that the SI can indicate a balanced condition, even when it isn't, so that result may be suspect.

Now this makes sense to me, mainly due to entropy, basically meaning that everything wants to balance out. Ca is a metal, and if you don't have metal ions in your water, the water "wants" them, and will pull them from whatever availible source. This may be the ladder in your pool, your heat exchanger in your heater or the metal parts in your pump. If you kick a bit of Ca into the water, you satisfy that need, and then the water doesn't attack metal parts.

The other interesting thing is that I think that the needed Ca level is low enough, that it is probably naturally found in the fill water used for pools.
So, it may not be a matter of needing to add Ca, you may just need to check to see if you have enough.

Comments?

Michael

[waterbear]

Langelier SI was designed for closed systems, not open systems like pools. It has some merit as a general guide but when you consider that pools are also balanced using the Ryznar(once again, from my understanding, usually applied to boilers and such) and Hamilton indexes and what is balanced with a certain set of readings in one is sometimes not in another makes you realize that they are just guidelines after all. It is interesting that a pool that is in balance by Langlier's equation might show up as corrosive under Ryznar. Which is correct? It is intersting that in the Langelier index(SI=pH+TF+logCH=LogALK-constant) pH is the factor that has the MOST influence in changing the output with lower pH making the water more aggressive and higher pH making the water more scaling. pH is the only factor in the equation that is used directly, Alk and CH are both used as a log10 of the reading which means big changes in the reading will only create small changes in the outcome of the equation. Temperature is, from my understanding of the equation, the second most changeable factor in the outcome of the equation since the Temperature Factor is the second largest changing variable in the equation. My feeling is that these should be taken as general guides and not as gospel as they often are in the industry and in the pool stores. I don't have the answers on this one but would sure like to know. I am currently running my pool using the Hamilton index which balances the TOTAL (not calcium) hardness and total alkalinity and the pool is run at a higher pH and buffered usually with borates (Borax, Supreme, Optimizer, etc.). This one was developed by the pool/spa industry and from what I understand has about 10 years or so of empirical evidence to back it up.
PoolDoc has an interesting article on high pH pools on the Poolsolutions website.
http://www.poolsolutions.com/gd/hiphpool.html
Would love to hear his take on all this. I DO keep some calcium in my fiberglass pool becuase I fill with water with 0 ppm hardness and I do have grouted tilework and a marble spillover in my spa. I keep my calcium at around 150 ppm. I just hope I'm doing it right but I guess only time will tell!
mwsmith2, I have to say your logic does make sense to me. Don't know if you are right or wrong but I think we are basically on the same wavelength.
Since I have a SWG and my pool seems to like to stabilize at around 7.8 pH it seems like a high pH pool was the easy way to go for me (I've said many times before in this forum that I'm lazy!)

[ldsmommyof12]

So, with all the above posts, please tell me the basic, final idea on calcium raising in a vinyl ag pool. I just tested and my calcium needs 5.5 pounds. Should I just disregard this since I have a vinyl ag pool? Thanks,

[CarlD]

So, with all the above posts, please tell me the basic, final idea on calcium raising in a vinyl ag pool. I just tested and my calcium needs 5.5 pounds. Should I just disregard this since I have a vinyl ag pool? Thanks,

Yes. Waste of money, potential problems.

MWSmith2 is addressing a theoretical problem that MAY be true. It may turn out that corrosion can be reduced with a little calcium--or another metal. He's talking about the electrolysis principles...Boat owners have for years had "Zincs" on their boats for the water to "eat" rather than their bronze propellers.

But Michael is tossing out a hypothesis for discussion. It may be turn out to be true, may not.

Now as to your "needing 5.5 pounds": what is your current Calcium level and why has that much been recommended to you, other than to generate a fund transfer from you to your pool store?

If your calcium is higher than 0, say, around 100ppm (low for concrete, fine vinyl) even Michael's theoretical concern shouldn't apply.

So post that number and we should be able to relieve your mind--and save you from getting "Pool Stored!"

[mwsmith2]

Yeah, it looks like if you've got 100 - 150 ppm you should be fine. More than likely they are trying to get you up to Ca levels for a gunite/plaster pool, which you simply don't need if you have a vinyl pool.

[PoolDoc]

Amazingly enough, I was just about to start a new thread when I saw this one. My basic premise is this:

All pools need some calcium

Now my above conclusion is based on the the Langelier Saturation index. I suppose the real question is, do you believe in the SI or not?

For what it's worth, Dr. Langlier didn't . . . at least for pools! He was rather dismayed to see his boiler corrosion index, for use in closed systems NOT exposed to air, applied to pools. I've got a copy of a letter he wrote on the topic somewhere. If I ever run across it again, I need to scan and post it!

Here's the deal. With the SI, you want to keep your water "balanced". That is to say, not in a corrosive condition, and not in a scaling condition. I was answering some questions today on here, and ran a few scenarios through the SI calculator found here:

No calculator links here, please!

I put up my own calculator a few years ago, mainly to try to correct the false impression of precise Langlier values given by calculators like the one you linked to. The Langlier index is a composite value, calculated from a conglomeration of approximate values. As a result, it's even MORE approximate.

What I mean is, if you test and find the following values:

• pH => 7.6,
• Alk => 110,
• Cal => 180,
• Temp => 83, &
• TDS 1200; and
• a calculated Langiler of -0.1 (which is 'excellent')

then you can assume that the

• ACTUAL pH is between 7.4 & 7.8,
• your ACTUAL Alk is between 90 & 130,
• your ACTUAL Cal is between 150 and 210,
• your ACTUAL temp is between 80 & 86, and
• your ACTUAL TDS is between 500 and 2000,

assuming you used a PS233 + an uncalibrated pool store thermometer + a Hanna TDS meter. In this case,

• the ACTUAL langlier index would be between -0.3 and + 0.55, or
• somewhere between a little low and definitely too high!!

The range of possibilities gets much wider, if you use test strips, or have water carried in your car all day tested at the dealers!

The point of all this is that, unless you are going to to lab qualities tests, doing the titrations with precision burets filled with reagent grade chemicals, and using a *calibrated* pH meter and a *calibrated* digital thermometer, and a *calibrated* TDS meter . . . your pool test measurements aren't really accurate enough to generate a meaningful Langlier index or Ryznar index (the Hamilton Index is a 'seat of the pants' index).

Fortunately, it doesn't matter!

There has NEVER been any research (at least that I have been able to find) that shows that the Langlier works for pools. The ONLY research I have on that topic, done by John Wojitiowicz, who was Olin's pool chemical research chemist for years, suggests it does NOT work, and that pH and alkalinity are much more important than the other factors.

This fits very well with my experience: old pools where the pH and alkalinity were controlled have decent plaster -- regardless of whether they paid attention to calcium or not. Old pools where they had pH 'accidents' have been replastered.

Put another way: commercial pools that used bleach (which is higher in pH) may have some stains on the plaster, but it's still sound. Commercial pools that used tri-chlor (low in pH) have usually be replastered one or more times, over a 15 year period.

These facts may explain why I try to de-emphasize the Langlier and Rynar indices. The Hamilton index is really a rough, seat of the pants, index that was mainly designed by Jock Hamilton of United Chemical, so those who 'had to have' an index, had one. It favors high pH, because high pH favors the bromine chemistry that's in virtually every product United sells.

But, wait, there's another HUGE error in the way the Langlier index is applied to pools! The one place where the Langlier is most likely to be meaningful, is inside the heat exchanger of a pool heater. Yet, I've NEVER seen anyone publish a comparision between the Langlier Index of a pool, and the index INSIDE the heat exchanger of a heater used on that pool. Take the pool above, with a 'theoretical' index of -0.1 . . . and add 30 degrees F.

Whoops!

All of a sudden, that nearly *ideal* index of -0.1 becomes a not so ideal index of +0.3 . . . and it does so, right where it can do some damage. So, now what should you do? Run a pool at around -0.4, so you can be fairly sure to maintain a SI of 0.0 or below in the heater? Or run an *ideal* SI of say, +0.2, and the HECK with the heater, at say, +0.5???

(If you notice, the recipes I give people tend to run low on the Langlier index. This is ONE reason why!)

There's more, of course. But I hope this explains adequately why I don't get all charged up about teaching all PoolForum users how to use the "Langlier" or "Ryznar" or "Hamilton" indices.

Ben
"PoolDoc"

[waterbear]

Bravo Ben! You reinforced some conclusions I had arrived at on my own from what I little could find out (Spent a lot of time researching boiler systems on the net!) and you cleared up some others for me. Thank you! I have gotten treated like a heratic when I have said to people that SI is intersting but don't loose a lot of sleep over it! (I dont DARE say it at the Pool store I work at part time....could cost me my job!) Am wondering though, what is your current take on high pH pools? From what I have been seeing the "Supreme pool algae reducers and water Opitmizers" (basically expensive borax) that are on the market have people running their pH on the high side which makes perfect sense if borates become a primary buffer system in the water.