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How to Maintain Swimming Pool Water

t’s all about the water.  In order to make your pool look inviting, you need to keep the water crystal clear.

You do not have to be a chemist in order to maintain the water quality in your pool.  However, you should understand the components that make your pool water safe and ideal for swimming.   The components are tested based on a parts per million (ppm) measurement.  This is the measurement of the parts of a substance in relation to one million parts by volume of pool water.

How to Test Swimming Pool Water

Using the test strips from the pool supply store should be sufficient for testing.  Water test strip containerGet the strips that show the chlorine, alkaline, pH, and cyanuric acid.  Find an area away from the skimmer and the returns and with the strip in hand submerse about 18 inches into the water for about 10 seconds.  Remove but don’t shake water off.  Wait a few moments until the colors fill in.  Compare each component’s color reading to the color range on the product bottle. (Read the instructions that were provided with the test kit as this procedure could vary from product to product).


The pH balance of your water impacts the effectiveness of the chlorine in your water. The idea test reading for pH is between 7.4 and 7.6.  If the test reading is below 7.2 then the water is more on the acidic side. A test reading above 7.8 indicates the water is more on the alkalinity side.  Monitor the pH daily using test strips.


To keep bacterial, pathogens, and algae from growing in your water, the chlorine (sanitizer) level needs to be at a safe level for swimming.  A chlorine test reading between 1.0 and 3.0 ppm is optimal.  If you use bromine tablets instead of chlorine as the sanitizer, then the reading should be between 2.0 and 4.0 ppm.  Ask your pool store for more advice on the pros and cons of using bromine instead of chlorine, or if you want to switch over to bromine from chlorine or visa versa.  Monitor the chlorine level daily using the test strips.



The alkalinity reading should be between 100 and 120 ppm.  Typically goes hand in hand with pH.  If the alkalinity reading is low, then most likely the pH reading is low and visa versa.  Typically chlorine shock contains alkaline which will help raise the alkaline level.  On the flip side of that, chlorine tablets which contain cyanuric acid tends to lower the alkalinity.

Cyanuric Acid

The cyanuric acid (chlorine stabilizer) reading should be between 20 and 30 ppm. This component is usually a product of chlorine tablets.  It slows the escape/evaporation of chlorine which in turn helps to maintain a more consistent chlorine level.  However, since chlorine tablets contain this component which is an acid, it tends to lower the alkalinity and the pH.

Safety Considerations

Consideration to keep in mind when dealing with pool chemicals:

  • Always follow the manufacturer’s instructions and warnings as indicated on the label.
  • Don’t mix any chemicals together.  Add each separately to the pool.
  • Wear protective safety glasses and avoid breathing in vapors when applying.
  • Store chemical in a cool, dry, and shaded area out of reach of children and family pets.

How to apply pool chemicals

If your pool is sanitized using chlorine chemicals, then the two primary applications you’ll want to use in your pool are chlorine shock (I like the granular shock that is package in 1 pound bags) and the chlorine tablets (I prefer the 3 inch tablets that you add to the chlorinator).

If your pool is sanitized with a chlorine generator system that produces chlorine from salt added to the pool, then you won’t need to add chlorine chemicals at all. You just need to add salt occasionally to the pool and adjust the main control unit to increase the amount of chlorine release.  Ask your pool installer or pool supply store for advice on this.

Baking soda (sodium bicarbonate) is an idea ingredient for raising the alkalinity and the pH.  Other products like pH Increaser and Alkaline Increaser are available at the pool supply store.

Adjusting Pool Water After Pool Opening

When you first open your pool, you should get the system running before adding the initial dose of sanitizer via chlorine shock.  However, if you have a chlorine generator, you only need to add salt to the pool so you can skip to the the Adjusting the pH and Alkalinity section.

If applying chlorine shock, then for example: a 16’ by 32’ pool which is about 20,000 gallons, one pound of shock should raise the chlorine level to 2 ppm.  You should probably add 2 pounds to kill all the bacteria and get the level to 4 ppm.  After this you may need to add more if the chlorine level doesn’t rise to the appropriate level. I would not add any more shock for at least a day or two after the initial dose.  Also wait about two days before adding the (chlorine or bromine) tablets to the chlorinator.  Otherwise your chlorine level may be too high.  Also, do not add (chlorine or bromine) tablets to the skimmer basket.  Doing so will reduce the life of the pool pump and filter.  Getting the chlorine to the correct level after pool opening can be tricky.

Applying Granular Shock to your pool

Granular shock should be mixed with water before adding to the pool.  Otherwise it could reduce the life of your vinyl liner.  When mixing granular shock, wear safety glasses and rubber gloves.  Using a 5-gallon bucket, insert 1 pound of granular shock. Be careful not to inhale the vapors or dust.  Add water to fill about ½ way with a hose (be careful of splash back) and stir very well with a wood stick.  Pour the mixture slowly into the water on the pool steps. If there are any granules left on the bottom of the bucket (there usually is) then add more water and stir and pour this in again. As with all pool chemicals, keep children and pets away from the bucket when mixing and keep everyone out of the pool when adding to the pool.  The best time to apply is in the evening because the chlorine won’t escape/evaporate (sunlight causes this).  Also, you must keep everyone out of the pool for about 8 hours after shocking to allow time for the shock to circulate throughout the pool.

On a routine basis, apply one pound of shock about every 10 days to keep the pool chlorine level active.

Applying Chlorine Tablets

Chlorine tablets can be added to the chlorinator.  Usually 2 or 3 at a time should last about a week before you need to add 2 or 3 more.  You can also put chlorine tablets in a floater basket but remove the floater basket before swimming.  Do not put tablets in the skimmer basket.  When you open the chlorine tablet container, avoid inhaling. .  Keep children and pets away also.  After handling the tablets rinse your hands off in the pool water.  Avoid touching your eyes.

Adjusting the pH and Alkalinity

Raise alkalinity and pH with baking soda If the alkaline is low, try add baking soda to the skimmer in the morning.  You could also add ‘alkaline increaser’ or ‘alkaline up’ if you don’t want to use baking soda.

Keeping a pH reading around 7.4 and 7.6 is the best level for your swimming pool.  It is easiest on your eyes and the pool parts and equipment.  If it is lower than 7.0 then most likely the alkaline is also low. Adding baking soda or ‘alkaline up’ should raise the pH also.  If the pH is still low after a day or two, then try adding pH increaser.

If the pH and alkaline are too high, then the water tends to get cloudy and this condition could invite algae growth.  Under these conditions, I would get the ‘alkaline decreaser’ or the ‘pH decreaser’ from the pool supply store.

If the cyanuric acid is too high, then I suggest backing off on the chlorine tablets since these contain cyanuric acid.  Shock doesn’t have cyanuric acid and can be used temporarily until the cyanuric acid levels come down to normal.  If this is the case, try adding 1 pound of shock (using the mixing method in the bucket and apply to pool steps) about every other 3 days for about 2 weeks.  Then return to the tablets.  Ask your pool supply store for more advice on this if the condition continues.  They may recommend draining a few inches of water from the top of the pool.  The cyanuric acid tends to hang on the top.

Green Water Trouble Shooting Tips

If you pool water turns green, this could be caused by algae growth if the pH is too high or if the chlorine level is too low. Adding chlorine tablets (sanitizer) should alleviate this. If the pH remains high then add ‘pH decreaser’ or ‘pH down’ and follow the instruction on how to apply.

If the pH is low and the chlorine is 3.0 ppm and the water remains green, then this could be an indication that your water has a high copper level.  Have your water tested at the pool supply store. There are products at the pool supply store that can remedy this situation.

Green water could also be an indication your filters are dirty or coated with tree pollen.  This usually happens a day or two after you add shock because it breaks down the yellow/green pollen material collected on your filter that is eventually pushed back into pool.

To remedy this, pull the filters and hose them off. Add baking soda and within a day or two the water should clear.

Routine Maintenance to keep pool water crystal clear

On a daily basis, remove any leaves and debris from the skimmer basket.  Also check the pump trap basket to see if this has a lot of debris floating around.  Occasionally empty this as well.

Remove leaves and bugs that are floating on top of the water with your hand held leaf net or hand held pool skimmer.

Also keep the filtering system clean.  Backwash filters or remove filters from housing and hose off about every two weeks or so.

Test the water with test strips to check the component levels.  Make any necessary adjustments that are needed.



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