Electrolytic chlorine generation can simplify some aspects of pool maintenance \u2014 but it requires adjustments in others.<\/p>\n
If there\u2019s one ingredient that most pool chemical regimens have in common, it\u2019s chlorine. Almost since the beginning of the pool industry, service technicians across the country have been hauling around drums of the sanitizer, using test kits to monitor its concentration, and adjusting water chemistry to maximize its effectiveness.<\/p>\n
But over the past decade, a growing number of pools have switched to a somewhat different system: Electrolytic chlorine generation. By using electricity to drive certain chemical reactions in salt water, electrolytic chlorine generators (ECGs) produce chlorine on-site.<\/p>\n
Although the chemistry of an ECG-chlorinated pool bears many similarities with that of a traditionally chlorinated pool, it also involves some unique factors.<\/p>\n
Here, through the expert advice of scientists and service techs, we examine these differences and provide some field-tested advice for servicing pools with ECGs. However, the ECG itself adds some new tasks to the traditional maintenance regimen. Among the most important is keeping the salt cell clean. The chemical reactions involved in generating chlorine from salty water also contribute to the accumulation of calcium scale within the ECG \u2014 over time, this can lead to less efficient chlorine generation, or even equipment damage. Thus, it\u2019s crucial to perform regular checks on the cell, and address any scale buildup with a light acid wash.<\/p>\n \u201cThe first year of a new ECG\u2019s life, you can usually get away with cleaning the cell once every three or four months,\u201d says Cliff Brummett, owner of CTB Pools LLC in Phoenix. But year by year, Brummett goes on to explain, the process of chlorine generation tends to drive the water\u2019s calcium hardness and alkalinity upward, making more frequent cleanings necessary. \u201cBy the second year,\u201d he says, \u201cyou typically have to start cleaning the cell every month.\u201d<\/p>\n Salt water, and the process of electrolysis, can also contribute to certain kinds of degradation, such as galvanic corrosion. In fact, says Alison Osinski, Ph.D., principal-owner of Aquatic Consulting Services in Avalon, Catalina Island, Calif., \u201cSome manufacturers may say their components were not NSF tested in salt water pools, and therefore [using them in a salt water pool] voids the warranty.\u201d<\/p>\n This is especially a concern for small components in heaters, such as gaskets and O-rings. \u201cYou\u2019ll need to pay more attention to those components, and replace them more often than you would in a traditionally chlorinated pool,\u201d Osinski says. Weekly checkups of these components, and replacements of any that are beginning to show signs of damage, will go a long way toward keeping the equipment trouble-free.<\/p>\n Another consideration, which might seem obvious but is often neglected, is the fact that the system\u2019s pump must be running in order for the ECG to produce chlorine. \u201cSince pumps on residential pools usually don\u2019t run 24 hours a day, we can get problems with these residential systems that we don\u2019t see with commercial systems, because they don\u2019t circulate the water enough,\u201d Osinski says. Thus, it\u2019s important to be sure the system is generating enough chlorine to maintain a proper residual in the time it takes the pump to run through one daily cycle.<\/p>\n Balance concerns<\/strong> However, there\u2019s one important respect in which ECG-chlorinated water differs: its level of total dissolved solids (TDS). Whereas most traditional recommendations place the ideal range for TDS at approximately 300 to 1,800 ppm, salt water often contains 3,400 ppm of TDS due to the salt alone \u2014 in addition to as much as 1,000 ppm of other miscellaneous TDS.<\/p>\n ECG manufacturers typically specify an ideal range of salinity for pools using their devices \u2014 so it\u2019s important to check the salinity of the water at least once a month. When performing these checks, be sure to use a test method that measures the salinity level in particular; not just the overall TDS \u2014 test kit instructions will specify which parameter each test addresses.<\/p>\n \u201cA standard TDS test is going to measure all the salt, plus any other dissolved solids,\u201d explains Ray Denkewicz, worldwide product manager for sanitization and chemical automation at Hayward Industries in North Kingstown, R.I. \u201cSo you might get a reading of 5,000 ppm, when in fact the salt contribution to that may be 3,000.\u201d<\/p>\n Thus, distinguishing between these two types of TDS contributions is critical for maintaining balanced water. And an effective way to get a clear sense of the pool\u2019s non-salt TDS is to perform a TDS test when adding salt to the pool for the first time. \u201cThat\u2019s your starting TDS,\u201d says Geoffrey Brown, developmental scientist at Pristiva Inc. in Overland Park, Kan. \u201cOnce your TDS increases 1,500 ppm above that, then you should start thinking about draining some of the water and replacing it with fresh water.\u201d<\/p>\n ECGs\u2019 tendency to drive pH and total alkalinity upward can impact other chemical parameters as well. \u201cNot only can high pH result in bather discomfort, it also makes the chlorine less effective,\u201d Brown says. This means that while a chlorine test might show that the water\u2019s chlorine level is acceptable, if the water\u2019s pH is too high, that chlorine will exist in a much less effective chemical form. Thus, weekly pH checks are essential for effective sanitation.<\/p>\n In these high-pH conditions, some say they\u2019ve found that higher TDS creates a greater potential for calcium carbonate and other soluble calcium compounds to form scale deposits on surfaces throughout the pool and equipment. \u201cThe calcium will want to precipitate out of solution,\u201d Osinski explains. \u201cIt can start clogging the pipes up, creating milky water, and causing scale.\u201d<\/p>\n However, other scientists point out that a higher TDS would actually lead to more corrosive water, by lowering the water\u2019s Langelier Saturation Index (LSI) value. \u201cHigher TDS makes the water more corrosive,\u201d says Karen Rigsby, leader of technical services at BioLab Inc. in Lawrenceville, Ga. \u201cIt\u2019s inside the chlorine generator where you get the likelihood of scale formation, and that\u2019s because of the high pH inside there.\u201d<\/p>\n If calcium scale does become a problem in an ECG-chlorinated pool, experts say it\u2019s generally reasonable to adjust the pH slightly downward with muriatic acid. Still, it\u2019s a smart idea to calculate the water\u2019s LSI value on every visit to the site, and visually inspect surfaces for any signs of corrosion, as well as calcium deposits.<\/p>\n Additive interactions<\/strong> As many service techs know, CYA is a chemical that protects chlorine from breaking down under the sun\u2019s ultraviolet (UV) rays. Many traditionally chlorinated pools are chlorinated with trichlor tablets, which contain both chlorine and CYA. However, the chlorine in ECG-chlorinated pools must also be protected with cyanuric acid (CYA) \u2014 industry organizations like the APSP recommend an ideal range of 30 to 50 ppm \u2014 which means it\u2019ll be necessary to add this chemical manually from time to time. Techs say approximately once per year is usually sufficient, but it still pays to test the pool\u2019s CYA concentration every month to ensure that the level hasn\u2019t dropped due to splash-out or backwash.<\/p>\n \u201cBut CYA doesn\u2019t degrade,\u201d Rigsby says. \u201cIt\u2019s not something you have to replace all the time, but you want to keep an eye on it.\u201d<\/p>\n Some service techs even recommend switching to tablets during colder months, when certain ECG models automatically shut down. \u201cWe use tabs during the winter, because our water gets colder than 55 degrees, and most cells shut off at 55,\u201d Brummett says. This can help prevent algae blooms and other microbe infestations during the winter.<\/p>\n Trichlor tablets contrast with ECG chlorination in another way, too \u2014 while these tablets tend to drive the water\u2019s pH downward, the pH of an ECG-chlorinated pool tends to drift upward (as discussed in the \u201cBalance concerns\u201d section earlier). This means the water balance regimen that keeps traditionally chlorinated pools balanced can send an ECG-chlorinated pool\u2019s LSI value well above the acceptable range.<\/p>\n Sequestrants can lead to a few problems in ECG-chlorinated pools. Some simply aren\u2019t as stable in the presence of high levels of chlorine \u2014 in other words, the levels inside the ECG itself \u2014 which can make them less effective. Also, some sequestrants are based on phosphates, which break down into orthophosphates \u2014 chemicals that combine readily with calcium in the pool to form calcium phosphate on the ECG. In any case, many manufacturers make sequestrants that are designed specifically for use in ECG-chlorinated pools; the packaging will usually specify this.<\/p>\n Some dry acids \u2014 such as sodium bisulfate \u2014 can leave sulfates in the pool, and these can contribute to scale problems similar to those caused by phosphate-based sequestrants. \u201cAnd if you\u2019re unlucky enough to live in a part of the country where you\u2019ve got barium in the source water, then you can get barium sulfate in the ECG, and that is next to impossible to get off,\u201d Brown adds. Pool test kits don\u2019t generally include a test for barium; the best way to find out if it\u2019s in the local source water is to consult the municipal water authority.<\/p>\n Bromine may also contribute to ECG trouble. Though this chemical can be a helpful supplemental algaecide in traditionally chlorinated pools.<\/p>\n \u201cBut you don\u2019t want to use it in a salt chlorinated pool,\u201d Denkewicz says, \u201cbecause the bromide ions interact adversely with the electrodes in the cell.\u201d<\/p>\n As the ECG\u2019s electrodes make chlorine from chloride ions, they\u2019ll also make bromine from bromide ions. \u201cBromide is harsh on the sensitive electrode,\u201d Denkewicz explains; \u201cit can damage it, and decrease the overall lifetime of the cell.\u201d<\/p>\n Though these potential issues can cause problems for ECG-chlorinated pools, keeping them in mind will help ensure that many pitfalls associated with ECGs are avoided. As many ECG experts point out, chlorine is chlorine, no matter how or where it\u2019s generated and introduced into the pool \u2014 but even so, a proper understanding of issues unique to ECG-chlorinated pools can extend the life of both the pool and its equipment.<\/p>\n Source: Ben Thomas- Pool and Spa News | 12.30.2011<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":" Electrolytic chlorine generation can simplify some aspects of pool maintenance \u2014 but it requires adjustments in others. If there\u2019s one ingredient that most pool chemical regimens have in common, it\u2019s chlorine. Almost since the beginning of the pool industry, service … Continue reading
\n
\nPractical considerations<\/strong>
\nPerhaps the most obvious area in which ECG-chlorinated pools differ from traditionally chlorinated ones is in chemical transportation and storage. Because barrels of chlorine (or chemical compounds including chlorine) don\u2019t need to be trucked to the site and stored there, many safety issues associated with these barrels \u2014 such as fumes and spills \u2014 are no longer major concerns.<\/p>\n
\nWhen it comes to the chemistry of ECG-chlorinated pools, most of the acceptable ranges specified by organizations like the Association of Pool & Spa Professionals and the Independent Pool and Spa Service Association will still apply \u2014 in other words, the water\u2019s calcium hardness, total alkalinity, pH and temperature should be maintained in the same ranges as they would for a traditionally chlorinated pool.<\/p>\n
\nEven if the pool\u2019s water has been balanced into an ideal LSI range, it\u2019s still helpful to be aware of some additional chemical traits of ECG-chlorinated pools. Aside from their higher salt-contributed TDS, the other main chemical distinction of these pools is how their cyanuric acid (CYA) concentration must be managed.<\/p>\n