Aqua Pure Filters

pH

Source of pH

The term "pH" is used to indicate acidity or alkalinity of a given solution. It is not a measure of the quantity of acid or alkali, but rather a measure of the relationship of the acid to the alkali. The pH value of a solution describes its hydrogen-ion activity. The pH scale ranges between O and 14.
Typically all natural waters fall within the range of 6.0 to 8.0 pH. A value of 7.0 is considered to be a neutral pH. Values below 7.0 are acidic and values above 7.0 are alkaline. The pH value of water will decrease as the content of CO₂ increases, and will increase as the content of bicarbonate alkalinity increases. The ratio of carbon dioxide and bicarbonate alkalinity (within the range of 3.6 to 8.4) is an indication of the pH value of the water. Water with a pH value of 3.5 or below, generally contains mineral acids such as sulfuric or hydrochloric acid.

Treatment of pH

The pH can be raised by feeding sodium hydroxide (caustic soda), sodium carbonate (soda ash), sodium bicarbonate, potassium hydroxide, etc. into the water stream. A neutralizing filter containing Calcite (calcium carbonate - CaCO₃) and/or Corosex (magnesium oxide -MgO) will combat low pH problems, if within the range of 5 to 6. The peak flow rate of a neutralizing filter is 6 gpm / sq. ft. Downflow filters require frequent backwashing is required to prevent "cementing of the bed". A 50 -50 mix of the two seems to provide the best all around results. Upflow neutralizers don't experience the problem of "cementing" of the bed.