I have tried my hardest to warn people about salt water chlorination systems. They are not acceptable unless you plan to check and rebalance the pool water daily. IPSSA is the largest independant organization of pool professionals around. They have released their latest test results that verify just this. Basically, salt water chlorination systems only work in a completely contained lab environment with daily water modifications.
This guy goes over the results in his blog and says it in a way that is worth reading. Take the time to read it if you are considering a salt water pool.
posted by Steven Riley:
Now, as you look down this page, if you're saying to yourself, "I ain't reading all this", just stick with me for a few more paragraphs before you close your browser. I'll hit the highlights for those of you lacking the Geek Factor one might need to get all the way through a piece like this. And I encourage you to read at least these next few paragraphs. Because this is it; the Smoking Gun, as it were. This is a document that no one selling salt based chlorine generators can hide from. Because it is true, unbiased research, conducted by research scientists at Cal Poly State University, in real swimming pools built for the specific purpose of conducting research for the pool industry by the National Pool Industry Research Center.
IPSSA's research protocal #1 asked the simple question: Can a Salt Water Pool Be Maintained Properly With Once-a-Week Service?
The short answer is NO. And here's why: The research concluded that salt based chlorine generators "do not provide for stable, in-specification, pool water chemistry parameters". What they found was that the pH would rise "very rapidly" after the weekly adjustments were made. This is something that all of us who service pools on a weekly basis have known about salt based chlorine generators since they first came back into vogue around 2002. Of course, you can still find manufacturer's literature that swears salt based chlorine generators make pH neutral chlorine. I explained why that's a load of crap back on November 4th, 2006 in the blog piece Welcome to the Caveat Emptorium. Here's what I said then:
"Now, if you look up the manufacturers sales pitch stuff, this is where they get that myth that the type of chlorine they generate is pH neutral because these three thing [chlorine gas, caustic soda and hydrogen gas] balance each other out. Not true. Much of the hydrogen gas rises to the surface and leaves the water. It gasses off, being a gas and all. Duh. That reduces the amount of hydrochloric acid created, and so the caustic soda - sodium hydroxide - neutralizes the hydrochloric acid and what’s left raises the overall pH.
But if you’re a pool cleaner like me, you already knew that without all them fancy words. Because every week when you go to your salt pools, the pH is through the roof."
And here, five years later, IPSSA and the NPIRC have proved that I was right, proved it in their test pools monitored by their research scientists.
Now, what has happened in that five years? According to an article in Casual Living magazine, in "2002, only 15% of new pool installations were salt water. Today,  an estimated 70% of all new pools are being built with electrolytic chlorine generators and the nation has more than 1.3 million salt water pools".
In 2005, when the problems with salt chlorine generators began to present and people like me started talking about it, not only did the industry ignore what we were saying, but they made an active effort to thwart our message, with lip service to the problems we were reporting by promising manufacturer funded research. I remember around March of 2007 a group of seven salt system manufacturers claimed - via a Pool & Spa News article, "Coping With Salt" - that they were investigating these issues and that results would be forthcoming. But absolutely nothing ever came of that, except that those manufacturers redoubled their efforts to sell a salt system to every pool owner worldwide.
So now we have salt systems on about 40% of the pools out there, and the most credible pool & spa service association on the planet (IPSSA), after reviewing the results from the most credible pool & spa research entity on the planet (NPIRC), says that these things aren't manageable on a week to week basis.
But the damage is done. The money's been made. And the consumer is still left with the impression that Salt's Great, because that's what the Sales & Marketing Guys have been preaching at them for a decade. Unfortunately, if the Average Pool Owner goes off-script and tries to find any information on their own about salt, they're more likely to read the article in Casual Living about how great salt pools are than they are to read an article in Pool & Spa News about the results of IPSSA funded NPIRC research on the problems with salt pools.
And even though some of the manufacturers have modified their pitch to tone down their outrageous claims of the benefits of salt, while totally avoiding any admission that there's any downside to salt at all, you can still find manufacturers Living the Lie on "pH neutral chlorine". Like this ChlorKing pdf from January 2010, touting the delivery of pH neutral chlorine from it's X-Gen On Site chlorine generator. In bold print, no less. It used to be that nearly all the manufacturers would say it, but most of them stopped when they saw the writing on the wall about those pesky old facts finally getting into print somewhere besides a pool cleaner's blog.
Now, let's look a little bit deeper at the research that was done. If you want to read the full report, you can download it here, at the IPPSA website. The pools that were used for this research are located in San Luis Obispo, CA on the campus of Cal Poly State University. The pools are small, approximately 8,000 gallons of water. You can see the pools here, at the NPIRC website. They're located at the top of a hill, with a 7 or 8 foot chain link fence surrounding them. The deck area around the pools is large and there is no vegetation growing near the pools. So, although they get some debris blown in over the fence from the surrounding trees on the campus, I wouldn't say it comes close to the level of debris that we get here in Texas in our older city neighborhoods with mature, heavily landscaped yards and lots of pool side foliage and tree overhang. Too, the weather in that area is pretty mild, with the average high temperature in July being 80.3 degrees. Here in Dallas, our average high in July is 96 degrees, resulting in 88 to 90 degree pool water. So, it's a pretty safe bet that the average Dallas residential pool would have about 3 times the chlorine demand from the salt cell as would be required to maintain the FC's detailed in the NPIRC report.
Another reason I think that would be true is my own personal experience with other forms of sanitizer in different climates. I lived in San Diego, CA for many years, and I distinctly remember keeping my pools on the high side of normal FC with 1 to 3, 7 oz. tabs every week (3 tabs being a very big old deep diver), shocking the pool with a gallon of liquid chlorine about once every never. Here in Dallas, it's typical to add 5 to 6 tabs every week during the summer, and shocking with a couple lbs. of cal hypo (equivalent to 1 gallon of liquid) about every two weeks.
So, I bet that the salt cells at NPIRC were running about 20% to 30% output, whereas we run salt pools through the swimming season at 100% output. The result being that we have two to three times the output in high pH chlorine in our salt pools, resulting in a much more rapid rise in pH.
I would bet it's the same in Arizona or New Mexico, or to the east of me across the sunbelt all the way to Florida: Higher ambient temps and water temps resulting in higher chlorine demand, resulting in higher output from all those salt cells and higher and higher pH's.
You know, when I was younger and more naive about the motivations of industry and the products they sold, I used to have this theory I would share about 7 oz. trichlor tablets, and it went something like this; pool water, given the parameters we need to protect the plaster surface, which is basically an alkaline, high pH surface, tends toward high pH. And trichlor tablets tend toward low pH. The two create a symmetry, a balance of sorts, that results in pretty rock solid pH right where we want it to be at 7.5. Because week after week, on pool after pool, out in San Diego and here in Dallas - two areas with vastly different fill water - given a proper Corrected Total Alkalinity (80 ppm to 120 ppm) - I would see the same pH on all of my pools; 7.5. And as long as I compensated for the high pH of my other chlorine products (sodium hypochlorite in San Diego and cal hypo in Dallas) when it came time to shock by adding a little muriatic acid in the deep end, I had no problem maintaining that perfect pH. The result was I never scaled or etched a pool. And I used to think this was by design, that thought and effort on the part of the industry went into all this.
But the full court press to ram salt chlorine generation down the throats of the industry by the manufacturers has proved to me that the trichlor thing was just a coincidence, and the only real design is making money, even if it scales the pool, corrodes all the metal and erodes the stone and concrete.
Thank goodness for organizations like IPSSA and NPIRC and their efforts to bring the facts out into the light of day. Too bad they don't have the advertising budget the manufacturers have to neutralize the good they try to do.
posted by Steven Riley