Get the correct water testing results

For many of us, water chemistry is a murky concept to begin with. But it's particularly confusing when an unlikely result causes you to lose confidence in your water test. Is the test faulty? Is your water simply wrong? Has the world gone mad?!

Relax. The answers to these questions are no, maybe and yes, in any order you like. And likewise, simple answers and logical reasoning can explain that pH reading of 9.2, up from 7.4 only two days ago.

In times of doubt, always remember that chemistry is consistent and predictable. It has laws, and follows them to the letter. They have not been temporarily suspended for the duration of your water test.

Therefore, the most likely cause of your suspicious test result is not mystical in nature. It's either pilot error, degraded test products or some kind of water condition such as over-chlorination that is interfering with the test.

On the other hand, it may be that your water really is out of whack.

In either case, a little understanding of the causes of error in water testing can go a long way toward a higher level of accuracy and confidence in results.

Trust, But Verify

The first thing a typical tester usually does on finding a wild result, according to Joe Sweazy, technical sales and service manager, Hach Company, Elkhart, Ind., is try to confirm the result with another tester. If it's a homeowner or service tech on a route, that person is probably headed to the water-testing lab at the pool store.

But hang on a second. There's a simple way to figure out if you did the test right. Testing companies offer "standard solutions," water samples that come from the manufacturers' own professional labs with its precise chemical makeup printed on the side of the bottle - for instance, a pH of 7.6, alkalinity of 100, a hardness of 200, CYA of 50.

Test this water exactly the same way you did your pool sample. If your result matches the manufacturer's printed result on your standard solution, then your equipment and procedures are OK, and your pool really does have a problem.

"We offer these for free so you can 'test your test kit,'" says Wayne Ivusich, sales manager for the pool and spa industry, Taylor Technologies, Sparks, Md., and a CPO instructor instructor (he teaches the teachers) with an 18-year background in the industry.

"It's a way to make sure you're doing the test right, and that your answers are good. But if you're getting a weird result - say if the standard solution is 100 ppm for alkalinity and you're getting 50, something's wrong."

Has It Come To THAT?

It's an unpleasant consideration, but it may be time to read the test instructions. Experienced pool personnel are loath to do that, says Jody O'Grady, manager, customer and technical service at Taylor. "I think the big thing I've seen over the years, is that people think they know what they're doing before they read the instructions.

"Maybe you get into a routine, where you've done the test for so long that you think you know how to do it." But instructions can very often give clues to why a result is off. The test may have changed over the years, or the user may have picked up a different brand, which uses a different procedure. Sometimes it just reinforces the deliberate step-by-step process so essential to water chemistry.

"People might say, 'I've been testing for 30-some years, I know what I'm doing.' But you can't assume anything. And that's hard for people who've been out in the field for a long time," says O'Grady.

One item a tester will find on reading test literature is information on test interference due to the contents of the pool, particularly high levels of chlorine.

"The thing that is going to interfere most with an accurate result is a high level of sanitizer, chlorine or bromine," says Ivusich. That can mess up a lot of tests. It can even mess up its own test - the sanitizer level test.

"Another thing could be the presence of metals in a hardness test - copper or iron, sometimes manganese. You can get the wrong color, or no color at all. And that's the sign of metal interference."

Perhaps more often than not, an inaccurate test is the simple product of inaccurate test procedures. People like Sweazy, Ivusich and O'Grady, who talk to water testers as part of their livelihood, stress this point again and again. They note that for some reason, there is some uncertainty in the minds of the general water testing populace whether exact adherence to a water-testing regimen is important.

It is.

"I get this question all the time," says Ivusich, "People say, 'I'm supposed to put in five drops of reagent, is seven OK?'

"And I say, 'Of course not.'

"Then they say, 'How about three?'"

Details, Details

The basic idea is straightforward - amount and time and sequence are important. All reagents are designed to be added in a certain amount and order, and to be given a certain amount of time to develop a reaction.

"If, for example, you add too much neutralizer when you're trying to get a decent alkalinity test - well, that neutralizer has a very high pH itself, so you've ruined the result of your test right there," says Ivusich.

In short, precision in testing is important. And for people who like to cook with "a dash o' this, and a pinch o' that," it takes discipline and focus to follow each step deliberately and exactly. Even the way you hold a vial or look at a test tube can affect results.

"For example, in a liquid test," says Sweazy, "if someone holds the dropper at a 45-degree angle instead of a 90-degree angle, the drop size is different, and then of course your result will be different. The vertical drop is larger. Little things like that are important to accuracy."

Even the physical location of the test can influence the result, notes Ivusich. "I've seen people try to do a DPD test outside - on a beautiful, bright, sunny day, not a cloud in the sky - well believe it or not, that can alter how your water test is interpreted."

The sunlight changes how your eye sees the color, he says, so testers trying to match colors should face away from the sun to keep its rays from directly entering the eye.

The same thing is true with drop tests, he adds. Many testers start counting the drops while holding the sample tube at eye level - the wrong way to do it. The tester should look down into the tube to get the right view depth and color development.

"Try it sometime," Ivusich says. "Put color in a small comparator tube, and then hold it at eye level, and then look down on it from above - you're going to see different shades."

Tools Of The Test

The other suspect in a case of dubious test results is equipment. Reagents, especially, are a place to focus attention when seeking an explanation for a wild reading.

Many people are reluctant to throw away an old reagent bottle even when it's past its prime, says Ivusich. "I get a lot of questions like, 'My phenol red reagent is green when it's usually red, is it still good?' Or, 'My reagents are clear when they're supposed to be cloudy, is that OK?'"

Of course not. Like every other man-made material on earth, once reagents are produced they immediately begin the process of decomposition.

After two or three years, for most reagents it's kaput, he says. But certain things hasten their demise. There are four of them, to be exact: air, heat, time and sunlight.

With these elements in mind, then, there are a few easy procedures that will keep reagents fresher longer, and therefore help keep results from going haywire.

1. Keep the cap on tight.
2. Store between 35 and 85 degrees F.
3. Keep out of direct sunlight.

If everybody from distributors to service techs to end-users follows those three basic rules, he says, reagents will last a good long time and provide good, solid readings.

But of the three rules, the most important is temperature, Ivusich says. "The hotter the environment, the faster the reagent will degrade."

That is more of a challenge in places like Miami and Houston than it is in Maine. But with an awareness of the problem comes reagent care solutions.

"I know a lot of service techs that will take their reagents in their coolers with those frozen gel packs," Ivusich says, "to keep them cool because a lot of these trucks don't have air conditioning."

Besides getting too warm, the other degrading experience for a reagent is exposure to air, especially for certain types of chemicals.

Any time you see a reagent in an opaque container, whether it's a brown bottle or white jar, that usually means it's some kind of an oxidizer, and that will degrade faster if it's exposed to air.

"For example," says Ivusich, "take liquid DPD No.2. I've gone into many retail stores over the years where every cap is off of every bottle. And you go over and pick up the liquid DPD No.2 and instead of being clear it's pink or red. That is not going to give you an accurate result."

One Accurate Watch

To maintain accuracy, a tester need not remember a lot of rules; just be aware of a few things to avoid in equipment care - heat, air, sunlight and time - and keep test procedures tight.

And when a result seems odd, the one thing you definitely don't want to do is to keep repeating the test over and over, exasperation growing with each result.

"I just talked with a customer," O'Grady says, "who tested his water in six different ways, worried about getting an accurate reading. He used our kit twice, as well as other manufacturers', and he felt that since all of the answers were slightly different, they all must be wrong.

"It reminded me of that old saying, 'A man with two watches never knows what time it is.' But I just recommended using our standard solution, which tells the customer, if he's doing the test right, exactly what the reading should be."