Pool Water Chemistry

pH Level

The pH level of the water is probably the most important factor in maintaining the pool water.  All other chemicals and levels depend on proper water pH.  PpH is also one of the most neglected levels.

pH is based on a scale from 0-14, 7 is considered to be neutral.  Anything below 7 is considered acidic and anything above 7 is considered to be alkaline.

Proper pH level in a swimming pool is around 7.4 to 7.8.  (a little alkaline), this level is less irritating to eyes, skin and pool equipment.

If the pH of your pool water is above 7.8, you will want to add an acid to bring the pH into the normal range.  If your pH is below 7.2, you will want to add a base to bring the pool water up to the normal range.  You can find the proper acids and bases at your pool supply store.  Always follow the dosing guidelines to prevent over adjusting.

Some problems with pH below 7.0 include:
·         Pool water becomes acidic
·         Irritation of eyes & skin
·         Chlorine dissipates much faster, requires more chlorine to be effective
·         Plaster pool walls deteriorate, the acidic water etches or dissolves the surface
·         Metal pump and heater parts corrode
·         Stains on walls from metals in water
To raise the pH level, typically you add soda ash (sodium carbonate).  Always follow the manufacturer’s dosing instructions.

Some problems with pH above 8.0 include:
·         Scale forms
·         Cloudy, dull pool water
·         Sand filters become clogged due to calcium carbonate deposits
·         Chlorine becomes ineffective, requires more chlorination
·         Irritated eyes and dry or itchy skin
To lower the pH level, typically you add muriatic acid (hydrochloric acid) or sodium bisulfate.  Always follow the manufacturer’s dosing instructions.

Total Alkalinity (TA)

To maintain proper pH of the pool water the Total Alkalinity must be in the correct range, the Total Alkalinity acts as a buffer or stabilizer for the pH preventing it from being volatile.  If your Total Alkalinity is not correct, you will have a very difficult time getting the pH correct.

The normal range for Total Alkalinity in a swimming pool is between 80 and 120 Parts per Million (PPM).  The effects of improper Total Alkalinity levels are similar to improper pH levels.

Some problems with Total Alkalinity below 80 ppm include:
·         Plaster pool walls deteriorate, become etched and the surface dissolves
·         Irritation of eyes & skin
·         pH levels erratic
·         Metal pump and heater parts corrode
To raise the Total Alkalinity, typically bicarbonate of soda (baking soda) or soda ash to the water.  Be sure to follow the manufacturer’s dosing instructions.

Some problems with Total Alkalinity above 120 ppm include:
·         pH levels hard to adjust
·         Chlorine becomes ineffective
·         Cloudy water
To lower the Total Alkalinity, typically muriatic acid or sodium bisulfate is added to the water.  Be sure to follow the manufacturer’s dosing instructions.

Total Dissolved Solids (TDS)

Total dissolved solids is basically anything in the pool water that isn’t the water itself. During evaporation of the pool water the only thing that evaporates is the water itself, all the additives, chemicals, dirt particles and everything else stay in the remaining pool water.  The accumulation of these things in the water is the Total Dissolved Solids.

The normal range for TDS is 0 t0 2000 parts per million (ppm), anything above 2000 ppm is considered high.  With a high TDS level the other pool chemistry levels can be very difficult to properly maintain and chlorine does not work as effectively as it should.

The only feasible way to bring down the TDS level in your pool is to do partial water changes to remove saturated water and add fresh water.  If the TDS level is extremely high, it may require a total drain and refill to remedy
 


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