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Water Testing

We are currently operating one of the largest, most sophisticated pool water laboratories in the United States. It is the only lab in North America running all three of the leading programs on a server.  However, it’s not magic. If you have a specific problem to be solved, we want to make sure that your expectations can meet our abilities.

Problem Solving.

If you went to the doctor, had the most complete blood work-up done, and never mentioned the pain in your arm, the blood lab would never know that you have a broken arm. Most pool problems are ultimately based on improper maintenance and circulation—which we can’t tell by testing calcium hardness!

The lab is the first place to start, but if you have a problem to solve, make sure that we know about it and address it. If there are people standing in line, it is not the lab technician’s job to solve your problem. Those of us on duty in the front of the Pool Store are available to help, so the technician can get as many people as possible in and out of the computer. Don’t rely solely on the print-out for problem-solving. We have many specific “Pool Tips” publications on common problems, and we’ll be happy to have a highly trained staff person deal with you specifically. Learn more at our Pool Tips Index page.

The Standard Water Balance Test

When you receive your print-out, check that we have the correct initial information: your name, chemical system, pool finish, and pool size. This is very important. If the computer thinks that you have 25,000 gallons of water, and you only have 2,500, you’re going to have massive overdoses of chemicals.  If you took a guess when you told us how much water you have, let us know, and we’ll help to figure it closer. We have a chart on our Pool Gallons page.

There are two parts to your print-out: water balance, and sanitizer problems. The sanitizer portion is for Now, because the sanitizer is what protects the health of all who use the pool. The water balance portion is for Anytime, because water balance affects mostly the long-term condition of the pool, water, liner, plaster, ladders and filter, while reducing the amount of money that you spend on pool care.

Within each part, you must follow the directions in order—there is generally a reason for the order. If you are told to wait a period of time between items, that period is a minimum. You don’t have to get up at 2 AM to do the next step. The waiting periods are there to allow certain processes to work before the next starts. Waiting longer than we tell you is generally fine.

Sometimes you can complete both portions simultaneously—if they don’t affect each other. Some exceptions to this would be a chlorine-based pool with a pH over 7.8 (the chlorine won’t work until the pH comes down), a pool using calcium hypochlorite chlorine with a saturation index over 2.0 (the chlorine may not dissolve properly), and a pool with high mineral or metal content (high sanitizer or oxidizer levels may cause a stain).  Let us be the ones to determine if you can take a shortcut.

If the computer recommends large amounts of metal chelators or sequesterers for copper in your water, check with us first. It takes a lot of copper to stain a pool, and you may not care if your walls are already blue. However, if you have a white plaster or vinyl finish, or if you use an expensive sanitizer, you should probably follow the directions. We will ask you about mineral ionizers you may use, or a heater. Sometimes, high copper levels indicate that something (actually poor chemical control) is ruining your heater!

We use computer programs by Baquacil, Bioguard, and Target. They prescribe chemicals in their own brands because it’s easiest for you to find them that way (and they wouldn’t mind the business).

We describe water balance theory, and the Langlier Saturation Index in our Pool Tips publication titled Water Balance. For now, suffice it to say that there are many ways to balance the same water, and the computer program normally chooses the cheapest method that still keeps all parameters roughly normal. However, the computer is not programmed to take into account what size containers that we sell. Most of us have the judgement necessary to round off the quantities requested on your print-out, so that your pool remains in balance, and you don’t waste money on purchasing chemicals that you don’t need right now. To learn more on water balance, go to the Pool Tips Index page

Our standard tests are designed to give you a complete water balance; usually taking seven to ten specific tests for your chemical system. You can see a list of all the standard tests that we do at Standard Pool Water Tests Available.

It is our pleasure to do the standard battery of water balance tests for you six times a year for each pool or spa, for free. We recommend two tests a year—opening and closing. A mid-summer test isn’t a bad idea, also.  We will be happy to do more tests than six a year, but there is a charge for them.  Prices are posted at the lab.

Additional Tests

Specialized tests are also available at Water Labs One and Two. If you would like to request any of these, there will probably be a charge, and we may need some extra time to complete it. Not everyone here has been trained in some of these tests that we rarely do.  A couple of these tests are a little dangerous to do.  If we request a specialized test ourselves, (generally because we want more information to help solve a problem for you), we will do the test for free.

There is a list of our specialized and research lab tests at Specialized Pool Water Tests Available.

Water Lab Programs

We operate the industry’s three best pool water programs: Alex by Bioguard, Waterlink by Target/Lamotte, and Clear Link by Baquacil. I believe that Alex is the best program for chlorine and bromine, but not for PHMB. It is complete in its explanations, it can handle pH corrections after it has made total alkalinity changes (not as obvious as it seems: changing total alkalinity changes pH, and also changes the rate at which pH changes), it is thoroughly tested before updates are sent out – it’s always right. For Baquacil users we use the Clear Link program. For Target pool chemical users, we use the Lamotte Waterlink program designed for Target brands. It is simple, does less advertising than Alex, and it can handle chemicals (like liquid super shock) that are not available from Biolab.

What does this mean to you? It’s really helpful to know your brand when you get to the lab – it will make your life much easier when you’re at the other end of the store and when you get home. If you have no idea, we will have a default to Target chemicals as they are most likely to be used by people who have no idea what they are using. We can’t tell by looking at what program you’re in. We put all of you in every program during the winters of 1999-2000 and 2002-2003 when we had software crashes and technology changes, to save time for you in May. Our cash registers do not interact with the water lab, so we can’t match what you buy with what you test. We can ask the cashier to look up your purchases, but when was the last time you gave the cashier your name when you bought pool chemicals?

It would be a good idea to check your printout every time you get a new one. Do we have your gallons correctly? That’s a big deal. How about your name? Did we just print out your brother’s pool with your results (sorry, it’s easy to do on a busy day, particularly if your name is Rob and your brother is Ron)? Do we have the correct sanitizer, shock, and algaecide? You could have changed since you were first put into the computer, and if you do not tell us, we’ll never know. You also could have left that blank and we put in a default. Whatever you were using may not have been an option in that program at that time. Let us know, and we’ll get it corrected for you. Sometimes it makes a difference; sometimes it doesn’t. It can’t hurt to get it right, though.


Please remember that we spend a great deal of time and money doing water tests.  It costs us around $10 per test, or close to $80,000 a year.  If you don’t want to wait, please give us a call—see if the lab is open, and if there’s a line. If you leave your sample here and you don’t wait, we will do the test when we can—but people waiting in the store always have priority of those who went home. Unlike just about every pool store in the world, we have a Night Deposit, so you can leave your test here even when we’re closed! To see more information on that, link to our Water Test Drop-Off page, or print out our Water Test Drop-Off Sheet and fill it out before you get here.  Please understand, though, we cannot read your results over the phone – you can only receive them in writing.  It is a safety issue.  We’re happy to mail, fax, hold for pick-up, or email.

Once again, it is our pleasure to help you. Learn more at the following pages:

Standard Pool Water Tests Available

Specialized Pool Water Tests Available

Water Test Drop-Off

Water Test Drop-Off Sheet

Please let us help you, anytime.


Pool Size: ___________ Gallons Technician: ___________
Date: ________________

We write Pool Tips for the exclusive use of our own local customers. They are meant as a summary of general information, to be discussed in our store, with our staff, to determine which items are best for specific pools. Pool Tips are a trademark of Gull Group, Inc. All rights reserved.

Our suggestions assume that you have given us a proper description of your pool’s size, history and symptoms. Sometimes we can figure it out, sometimes we can’t. Your doctor has years more training, far better diagnostic tools, and makes way more money—and sometimes he or she gets it wrong, too.

  1. Read all labels carefully, and only use chemicals exactly as described on the label. Never mix chemicals together outside of the pool. Some of them can cause a fire or explosion.
  2. Do Not follow any advice or suggestions here without coming into the store, customizing them to your specifics, and receiving them in writing.
  3. Do Not print these out or reproduce for any purpose whatever. They are all copyrighted, and we take our copyrights very seriously.
  4. Don’t Blame Us for anything. It’s free advice, and worth the price paid. We’re trying to help, but pools are complex, and chemicals and electricity are dangerous.
  5. Our Best Advice: Go find a local pool dealer who knows what they are doing, become a steady customer, and give them a chance to learn about you and your pool. Pick a brand, pick a store, and stay with them.