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Testing & maintaining the sanitizer level - No matter what basic chemistry or pool care sanitizing system you're using, chlorine, bromine, salt / chlorine, biguanides (such as BioGuard® Soft Swim®), or other alternatives such as Pristine Blue®, you have to keep an eye on that level.  Too low - bacteria & algae can get out of control & cause real problems.  Too high - that's just being wasteful; it's unnecessary to maintain high sanitizers levels in most swimming pool applications.  But sometimes you do want that sanitizer level a bit higher, like just before a big pool party or if your area is expecting a lot of rain.  That temporarily high sanitizer level will protect the pool water from getting "out of whack".  How many times have you been to or been the host of pool party and you can actually watch the water become hazy as the party goes on (then realize that hardly anyone has used the bathroom all day! Yikes!).  Starting a pool party with a higher sanitizer level could have prevented that.

But, you also have to know what sanitizer level you're testing.  Especially in the case of chlorine, which chlorine are you testing?  Free Available Chlorine (FAC) or Total Chlorine?  What's the difference?  FAC is the chlorine level that is actually active & working killing bacteria & algae.  Total Chlorine is exactly that - the total amount of chlorine present in the pool, FAC plus combined chlorines.  And you don't want combined chlorines.  Combined chlorine is chlorine plus waste; usually in the form of nitrogen (chloramines).  It smells & causes red eyes.  When you have a strong chlorine odor, the cause is typically a very poor level of FAC and a High level of chloramines.  The only way to get rid of them is shock the pool.  Click on this link for more information on chloramines & other chlorine issues. 

Here's quick chart as to proper sanitizer levels:

     Chlorine -  1.0 - 2.0 ppm (FAC)
     Bromine - 2.5 - 4.5 ppm
     Biguanide 30 - 50 ppm (SoftSwim, Baquacil)
     PristineBlue® 0.5 - 1.0 ppm

How often should you test the sanitizer level?  Ideally, every day.  Realistically, 2 times per week is great.  You may want to keep a log in case you ever need to treat a problem.  When you call us, we'll be able to help you diagnose that problem.

Testing & maintaining the pH - Here's the question that we're regularly asked: "Why do I have to test the pH? The water looks great and besides, the chlorine level is more important to watch."  Where's that buzzer? Wrong! Testing & maintaining pH is almost more important than testing for sanitizer.


With an improper pH level, nothing works the way it should! All pool sanitizers work best in a very narrow range of 7.2 to 7.8. 

If the pH is low (less than 7.2), you may have really clear water but, you'll burn through chlorine like crazy, your blonde hair will turn green, corrosion of pool surfaces & equipment will take place. We've even seen skin abrasions due to low pH ("but the water is SO clear!"). Low pH  causes rapid chlorine  use & many people blame a "low" Cyanuric Acid or stabilizer level.

Water with a high pH, sanitizers become sluggish & work slowly.  The results: hazy or cloudy water, scaling of pool surfaces & equipment begins to occur.  Physically, you'll also notice red eyes, itchy skin, dry hair.

When you notice the pH going off, either low or high, don't ignore it.  Correct it as soon as possible. Use pH increaser such as BioGuard® Balance Pak 200® when the pH is low.  Use about 1 lb. per 10,000 gallons.  Retest the following day.  Use pH decreaser such as BioGuard® Lo 'n Slo® to lower the pH when it gets high.  Use about 1 lb. per 10,000 gallons.  Retest the following day.  Always make incremental adjustments to prevent see-sawing.

Other important water balance levels - Water testing shouldn't end with sanitizer & pH.  There are other components that need to be watched for optimal sanitizer effectiveness, protection of pool surfaces & equipment, and swimmer's comfort & health.  These other water chemistry indicators are Total Alkalinity, Calcium Hardness, Cyanuric Acid (stabilizer), Metals, TDS & Chlorine Demand. 

Briefly, the Total Alkalinity (TA) is a buffer for the pH - good range 80 - 150 ppm, depending on pool surface type & type of sanitizer used.  If the TA is low, the pH will "bounce" around & you will have difficulty maintaining it for more than a couple of days.  If the TA is high, the pH will tend to be high which will contribute to scale build-up.  Calcium Hardness (CH) is the measure of how much calcium & other carbonates are in the water.   Low CH will lead to aggressive water (similar to low pH) as the water wants to balance itself & therefore eats away at any & all pool surfaces.  High CH will be shown as cloudy water, with the water becoming cloudier as the water warms - especially above 85 F.  Rapid scaling will also occur damaging filters & heaters.  High calcium is generally caused by using calcium based chlorines or from very hard source water.  TA & CH should be tested 4 - 6 times per season.  Once adjusted, they do not fluctuate wildly except in the case of heavy rains or copious amounts of make up water.  Learn more about Total Alkalinity & Calcium Hardness here.

Cyanuric Acid (CYA) - chlorine stabilizer - should be tested about 3 - 4 days after pool start up.  If you are using a slow dissolving chlorine stick or tablet, odd are that you WILL NOT need to add stabilizer every year.  DO NOT TEST FOR STABILIZER UNTIL THE FILTER HAS RUN FOR A MINIMUM OF 3 DAYS FOR ACCURATE RESULTS.  Do not randomly add stabilizer every year or pool season without first testing, you'll be wasting your money. Maintain a level of about 40 - 100 ppm. 

Something to keep in mind with CYA or stabilizer: many of the "cheap" chlorines & shock products use CYA as a filler product. High CYA (over 150 ppm) MAY lead to problems due to higher Total Dissolved Solids (TDS - or everything that is dissolved in the water). This has been a point of contention for many years with no resolution in sight. CYA or stabilizer should NEVER BE ADDED until first tested to be sure that there is a definite need (ie, a CYA level less than 20 ppm). 

Myth - there is no such thing as "chlorine lock" caused by higher levels of CYA.  This is more of a Chlorine Demand problem.  If you are using Bromine, do not test or worry about CYA, bromine cannot be stabilized. Ever.

Metals, TDS (total dissolved solids) & chlorine demand should be tested from time.  Tests should be performed by a qualified pool water professional.  If you suspect or are having staining problems, problems maintaining a sanitizer level, incurable cloudy water or algae, please bring in a one quart water sample for a free complete computerized water analysis.

Remember to follow the other 5 Keys to Pool Care.  They're just as important.

The 5 Keys typically take about ONE hour or less to accomplish each week.  Yes, that's it!  Just 1 hour.  Now you can enjoy your pool more & actually work less.  In the long run, you'll also spend less time & money.

The 5 Keys to Pool Care ... Key 4 - Testing

Here's what Pool testing involves:

- Testing & maintaining the sanitizer level - chlorine, bromine, salt level, biguanide (Soft Swim or Baquacil)
- Testing & maintaining the pH
- Other important water balance levels

Key 4 - Testing
Test your pool water at least 2 times per week & bring in a 1 quart water sample for a complete computerized test & analysis 3 times per season for best results.  Testing keeps you up to date on what's going on with your pool water

Don't rely solely on how the water looks.  In fact most of the SERIOUS water problems that we see (skin rashes, colored hair, pool surface etching, etc.) occur when the water is "crystal clear" about the middle of the swimming season. 

Make pH, total alkalinity & calcium hardness adjustments promptly.  You'll protect the filter system, the pool surfaces, get better chlorine & sanitizer efficiency and virtually eliminate red eyes & dry skin..