{"id":86,"date":"2012-03-27T22:55:19","date_gmt":"2012-03-28T02:55:19","guid":{"rendered":"http:\/\/expertpoolbuilders.com\/blog\/?p=86"},"modified":"2012-03-27T22:55:19","modified_gmt":"2012-03-28T02:55:19","slug":"perfect-water-balance","status":"publish","type":"post","link":"https:\/\/expertpoolbuilders.com\/blog\/perfect-water-balance\/","title":{"rendered":"Perfect Water Balance"},"content":{"rendered":"

To effectively preserve the pool\u2019s plaster life, techs must recognize common mistakes in calculating balanced water.
\n<\/strong><\/p>\n\n\n\n
Since \u00a0 the 1960s, the pool industry has relied on the Langelier Saturation Index to \u00a0 achieve balanced water. The traditional method has been to land right at 0.0 \u00a0 of an SI with an allowable variance in either direction. But the subtleties \u00a0 of pool chemistry call for both a studied approach and a modified SI range.<\/p>\n

Over \u00a0 the years, experts have seen two things: mistakes in calculating SI and a \u00a0 need for the Index itself to be adjusted. Here, we examine some common errors \u00a0 techs make in calculating each component of the Index, as well as the \u00a0 advantages of skewing SI balance toward a positive number.
\nBalanced water will go a long way in preserving the life of the plaster and \u00a0 the clarity of the pool.<\/p>\n

pH<\/span><\/strong>
\n<\/span>Measuring pH is the least problematic portion of the SI. There are no \u00a0 conversions necessary since the pH level is actually the number you\u2019re using \u00a0 to compute SI. Just be aware of anything introduced to the pool that may have \u00a0 an affect on the pH.<\/p>\n

The \u00a0 most obvious pH changes will be the result of introducing sanitizers into the \u00a0 pool. Acidic sanitizers like trichlor and dichlor will lower the pH. However, \u00a0 you should be cognizant of CO2 loss, which can be especially dramatic in \u00a0 spas.<\/p>\n

\u201cPeople \u00a0 forget that when you turn the aerator on \u2026 immediately the pH goes up,\u201d says \u00a0 Joan Vienot, owner of Pool Pal Inc. in Freeport, Fla.<\/p>\n

It\u2019s \u00a0 best to tabulate the water balance in a spa after the unit has already been \u00a0 used in order to account for these changes, she adds.<\/p>\n

Alkalinity<\/span><\/strong>
\n<\/span>As most techs know, alkalinity refers to the pool\u2019s ability to buffer the \u00a0 water against pH change. When calculating the Saturation Index, however, we \u00a0 are only interested in alkalinity\u2019s ability to keep calcium carbonate in \u00a0 solution.<\/p>\n

To \u00a0 calculate the correct SI factor, techs must isolate carbonate (or, in \u00a0 actuality, bicarbonate) alkalinity from the pool\u2019s total alkalinity.<\/p>\n

Though \u00a0 a host of buffers contribute to total alkalinity, carbonates and cyanurates \u00a0 make up the majority of alkalinity in most pools. This is particularly true \u00a0 in pools that are sanitized with dichlor or trichlor, which continually feed \u00a0 cyanuric acid in the vessel.<\/p>\n

In \u00a0 order to isolate carbonate- from cyanurate alkalinity, experts generally \u00a0 recommend taking a third of the cyanuric acid level from the total alkalinity \u00a0 reading. For example, at a pH of 7.5, a pool with 90 ppm of CYA would have \u00a0 approximately 30 ppm of cyanurate alkalinity, which you would have to \u00a0 subtract from the total alkalinity reading to find the necessary SI factor. \u00a0 Note that cyanurate levels at a higher pH will be more than a third of the \u00a0 cyanuric acid level.<\/p>\n

But \u00a0 remember, isolating the carbonate alkalinity is not correcting any kind of \u00a0 interference. The cyanurate is still buffering against pH bounce.<\/p>\n

\u201cThere \u00a0 are people applying that \u2018correction\u2019 to the alkalinity even when they\u2019re \u00a0 reporting total alkalinity,\u201d says Que Hales, a manager for Pool Chlor<\/a> \u00a0 in Tucson, Ariz.<\/p>\n

This \u00a0 mistake is especially troublesome because every time cyanuric acid is added \u00a0 to the pool \u2014 whether directly or through stabilized sanitizers \u2014 carbonate \u00a0 alkalinity actually is being transformed into cyanurates. Even with the rapid \u00a0 transformation of bicarbonates to cyanurates, the total alkalinity should \u00a0 remain a relatively stable pH buffer.<\/p>\n

TDS<\/span><\/strong>
\n<\/span>\u2014or in some cases 1,500 ppm \u2014 in the water. However, these tables were \u00a0 largely put together before salt-chlorine pools became popular.<\/p>\n

With \u00a0 salt levels of 3,500 ppm, many pools with chlorine generators have from \u00a0 4,000- to 5,000 of TDS in them. In these cases, even using the 12.2 number is \u00a0 hardly being accurate. Your water is much more corrosive than you may think.<\/p>\n

\u201cIf \u00a0 everyone will use 12.4 for the TDS factor, then the corrosive effect of the \u00a0 salinity will be accounted for,\u201d Vienot says.<\/p>\n

While \u00a0 Vienot uses a standard value of 12.4, chemist John Wojtowicz published an \u00a0 equation in 2001 to explain the changing SI values as the TDS rose over 2,000 \u00a0 and above. As demonstrated by the chart<\/a>, a normal \u00a0 salt pool will be improperly balanced if a tech uses a 12.1 or 12.2 constant.<\/p>\n

Calcium hardness<\/span><\/strong>
\nThe calcium component of saturation chemistry is often misunderstood. The \u00a0 actual contributing factor to saturation issues is the amount of calcium in \u00a0 the water. Calcium test kits give that value. However, some industry test \u00a0 methods give total harness instead, which includes calcium but also other \u00a0 components. To correctly calculate saturation values, use a calcium hardness \u00a0 rather than a total hardness kit.<\/p>\n

Although \u00a0 the calcium hardness level is a direct indication of how much calcium is \u00a0 available in the water to fall out of solution, it is not the primary \u00a0 indicator of whether calcium actually will precipitate. pH is the primary \u00a0 factor, with alkalinity in second place.<\/p>\n

And \u00a0 although lower calcium levels do limit the amount of precipitate that can be \u00a0 formed, you can\u2019t go overboard and maintain too little calcium.<\/p>\n

\u201cIf \u00a0 you don\u2019t have calcium added to water, it\u2019s going to leech the calcium out of \u00a0 that system,\u201d explains Greg Garrett, technical advisor for the National Plasterer\u2019s Council<\/a> in Port Charlotte, Fla.<\/p>\n

This \u00a0 is especially true of newly plastered pools that have not had adequate time \u00a0 for internal cement compound transformation, he adds.<\/p>\n

Temperature<\/span><\/strong>
\nTemperature is as straight-forward as pH, but perhaps because of its relative \u00a0 simplicity, many techs don\u2019t pay attention to the seasonal differences in \u00a0 pool and spa maintenance.<\/p>\n

Temperature \u00a0 is key to the SI because as the water heats up, calcium becomes much less \u00a0 soluble. This is why pools can deteriorate over the off-season and many spas \u00a0 are ridden with scaling problems in the summer.<\/p>\n

\u201cA \u00a0 perfectly balanced pool in the summer may be very corrosive in the winter,\u201d \u00a0 Vienot says. \u201cIn spas is probably where you get the most common water balance \u00a0 problems. If you balance them for cold water and then heat them up 60 degrees, \u00a0 you\u2019ve got some real problems.\u201d<\/p>\n

Even \u00a0 if all the other SI factors are within an accepted range, an unaccounted for \u00a0 temperature can quickly tip the water\u2019s balance.<\/p>\n

Proof positive<\/span><\/strong>
\n<\/span>The NPC\u2019s new start-up guide is now recommending an ideal range of all \u00a0 positive indices for maintaining pools and spas. This approach is to ensure \u00a0 that the calcium in the pool plaster is not etched out into the water.<\/p>\n

\u201cWhy \u00a0 tolerate negative indices, which indicates the water is under saturated by \u00a0 [at least] one parameter?\u201d Garrett says.<\/p>\n

Even \u00a0 APSP\u2019s recommendations call for an ideal range of 0.0 to +0.5, with an \u00a0 allowable variance on the negative side.<\/p>\n

Service \u00a0 techs generally agree.<\/p>\n

\u201cWith \u00a0 most pools, we intentionally ride the Saturation Index a little bit toward the \u00a0 positive side to where, if something goes wrong, we\u2019re more likely to scale \u00a0 it than we are to etch it,\u201d Hales says.<\/p>\n

However, \u00a0 some pools \u2014 those with exposed aggregate, water features that continually \u00a0 raise pH through aeration or sanitizers that require constant adjustment \u2014 \u00a0 may need the full range of the \u201cneutral zone\u201d of -0.3 to +0.5, he adds.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Source: John Miles- Pool and Spa News | 2.13.2009<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

To effectively preserve the pool\u2019s plaster life, techs must recognize common mistakes in calculating balanced water. Since \u00a0 the 1960s, the pool industry has relied on the Langelier Saturation Index to \u00a0 achieve balanced water. The traditional method has been … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[],"class_list":["post-86","post","type-post","status-publish","format-standard","hentry","category-fiberglass-pool-maintenance"],"_links":{"self":[{"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/posts\/86","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/comments?post=86"}],"version-history":[{"count":1,"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/posts\/86\/revisions"}],"predecessor-version":[{"id":87,"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/posts\/86\/revisions\/87"}],"wp:attachment":[{"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/media?parent=86"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/categories?post=86"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/expertpoolbuilders.com\/blog\/wp-json\/wp\/v2\/tags?post=86"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}