Swimming Pool Water Level

The level at which the swimming pool skimmers operate best is between one third and one half the way up the opening of the pool skimmer. If the level is higher, the water moving into the skimmer is going so slow that debris may pass by the opening without being pulled in. If the pool water is so high that it covers the skimmer opening, floating debris can’t get in. If the water is too low the skimmer can bottom out, thereby sucking air into the system which can result in losing the prime and possibly result in burning up your swim pool filter pump motor. Add water before backwashing and vacuuming the pool because this will also lower the water level. source – https://www.swimmingpool.com/maintenance/water-care/pool-water-level/

As most of you know, we have been treating water for over 40 years.  Over those years, we have come across some really amazing scenarios that are not in any text books or training materials. From treating poultry water to paper mills, private wells to surface waters, and of course swimming pools. We truly have experienced it all.  The one question that stands out the most is pH and the relationship to alkalinity.

pH is the single most misunderstood/overlooked variable in water treatment.  It is also the single most important.  Whether you are removing manganese from a water well or trying to clear up a swimming pool, you MUST have to consider pH first.

pH and alkalinity are two different measurable parameters of water.  pH is a measure of the acidity or basicity of an aqueous solution. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline. Alkalinity is a measure of the buffering capacity of water.  Or simply its ability to resist sudden changes in pH.

pH Concentrations Scale


What does the lower case “p” and the capitol “H” stand for?  In the United States, the “p” normally stands for “potential” and “H” stands for “Hydrogen”.  Therefore, pH stands for the potential of Hydrogen.  It is the hydrogen ion that determines the level of acidity or alkalinity.

An example of a weak acid is acetic acid (vinegar), which releases only small amounts of free hydrogen ions into solution. Sulfuric acid is considered a strong acid because it releases more hydrogen ions into solution. Highly acidic water can be corrosive. Note – all acids have an “H” in the chemical formula.

An alkali can be defined as a substance that releases hydroxyl ions when dissolved in a solution.  The higher the concentration of the hydroxyl ions in a solution, the higher the resulting pH will be.  Highly alkaline waters can dry out the skin.  Common alkalis include hydroxide, carbonate, and bicarbonate salts such as calcium, magnesium, potassium, and sodium. Note – All alkali have “OH” in the chemical formula.

Acid (H+) + Alkali (OH) = H2O


If your pH is over 7.0, your water is called alkaline.  You have too much OH floating around.  When you add muriatic acid for example, H+ will combine with OH and produce H2O and reduce your alkalinity and also reduce your pH.



If your pH is below 7.0, your water is acidic and contains too much H+.  Your alkalinity is probably too low in this situation.  When you add baking soda (sodium bicarbonate), the OH will neutralize the excess H+ to form H2O.  It will raise the alkalinity and raise the pH also.

Defined, alkalinity is the buffering agent that maintains/stabilizes pH.  In your pool, it dictates how fast your pH will rise.  This will vary by regions depending on the other dissolved solids in your water.  For most areas of the country, your pH will balance at 7.2 with an alkalinity of 60-80.  Keep in mind, this is a rule of thumb, and NOT the law.

You do not need to test for alkalinity often.  But when you are fighting your pH, it must be tested and noted in a journal.  If you are opening your pool and adding acid more than once a week, that is a great time to do an alkalinity test.  High alkalinity will drive pH up.  The higher the alkalinity, the faster your pH will rise

I will give you an example.  If you and your neighbor have a pool (same size, same surface, same bather usage) and you have an alkalinity of 200 and your neighbor has an alkalinity of 100, then your pH will rise twice as fast as theirs because your alkalinity is twice as high (again, just an rule of thumb and not scientific law).

Let’s say your pH is 7.8 and alkalinity is 200.  When you run your acid demand test and add the appropriate amount of acid, your pH may drop to 7.0 and your alkalinity may drop to 180.  Your pH will rise again and possibly be out of range in 2 days.  When you treat your 7.8 pH again, your alkalinity may drop to 160.  But instead of 2 days, it is 3 days before it reaches 7.8.  Each time you treat your pool with an acid, your alkalinity with drop.  Perhaps on the 4th or 5th treatment, your alkalinity will be 80 and remain in balance for 7 days without going over range (which is a maximum of 7.4 for ionization).  That is the sweet spot you are looking for.

Keep in mind this is merely an example.  You will have evaporation, splash out, make-up water, and rain.  Your pH will NEVER remain constant.  There are some automated systems than can measure pH and automatically add acid to your pool for a more hands free approach.  But maintaining pH is an ongoing effort and this is where you spend most of your time.

For an ionized pool, we do recommend testing twice a week.  The average person treats their pool by adding and acid or base once a week.  For those that do nothing, you are just lucky.  But we do have a few of those out there.

If this all sounds confusing, that is OK.  We have a toll free number to assist you with this and any other questions you may have regarding your swimming pool.


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