UNDERSTANDING WHAT YOU ARE TESTING IN YOUR POOL WATER CHEMISTRY
Understanding pH
We are going to start by talking about pH. This is a number which indicates the acid vs. base balance of your water. The pH reading will start from -0- and go through -14-. On this scale, the lower the number the more acidic your water. The higher the number, the less acidic.
An example to understanding pH and the scale would be to know that some of the hand or dish soap you generally use every day would rate somewhere between 12 to 13 on the pH scale and on the opposite end, muriatic acid used in your pool or battery acid inside your car battery would rate somewhere near zero. Perfect balanced pH, such as water bubbling up from a natural spring would rate somewhere between 7.0 to 7.2. This would be called the ideal range of pH and is the basis for how we compare your pool water. The pH of swimming pool water is kept slightly higher than spring water.
pH can be adjusted in your pool by adding alkalizer, which is a pH chemical like soda ash; even baking soda would do the same thing. To decrease pH you would simply add more acid. Muriatic acid is the most commonly used type of acid. The pH of you pool will need to be checked and adjusted periodically (usually once a week). The reason you need to check the pH is because it will be constantly changing due to rain diluting the water, excess use by swimmers, evaporation and many other environmental reasons.
IMPORTANTNEVER move the backwash valve while your pump is running! Make sure the pump and entire system (for added safety) are in the off position. It might be a better idea to turn the pool system breaks off just in case you have an automated system that could activate the system (due to its programming) while you are servicing it. Serious injury or damage to the system can occur if you do not follow this warning. |
Understanding Chlorine
Chlorine is a sanitizer and just like the word sounds, it sanitizes you pool water by killing the microorganisms that live and breed in the water. Chlorine is measured in ppm just like pH. The correct reading for you pool will depend greatly on the type of purification system you have. If you have no system and are just adding liquid chlorine into the pool then your reading, depending on use and climate will ideally be between 2.0 to 3.0 ppm. At 3.0ppm you will definitely smell and taste the chlorine in your pool while swimming. If you are using ozone your reading will be reduced to about .5 ppm, depending on the manufacturer specifications. An ozone system does some of the work in place of chlorine (oxidizing) thereby reducing the need for it. At .5 ppm you should not smell or taste the chlorine. In fact, at this reading the chlorine levels should be lower that the city municipal water in your sink at home, depending on where you live and if they sanitize the water at all.
There are many forms of chlorine, some of which you have probably already heard of. Don’t be intimidated by their proper names, they are all still just chlorine no matter what they are called. Liquid chlorine is also known as Sodium hypochlorite and granular dry chlorine is known as Calcium hypochlorite
The chlorine you put in your pool will be much more effective if the pH has been balanced. You will find that running high on your pH will make your chlorine far LESS effective. By contract, running low on your pH will make your chlorine more potent. What this means to you is that until you achieve a proper balance of all the entire pool chemistry, the general charts for how much of what to add may not seem to work out so well for you. Think of all the different parts of your pool chemistry as a “whole” or musical instruments that when working together in harmony produce the perfect symphony.
IMPORTANTFollow all safety guidelines for handling any chlorine product as directed by it’s manufacturer. |
Understanding Alkalinity
The total alkalinity is a measure of how much of the alkaline substances there are in your water. Total alkalinity is measured in ppm. The general recommended total alkalinity reading for your pool is between 80 to 120 ppm. With the total alkalinity in proper specifications it prevents pH from becoming unstable and helps keep the pH at a more constant level.
A result of the total alkalinity being too low would be the etching of the plaster inside your pool and corrosion of metal parts in your system. The interior of your pool surface can become stained as a result and you will find your pH reading bouncing all over the place from day to day.
As a result of the total alkalinity being too high you will find your pool water “milky” or “cloudy” and you will be constantly adding muriatic acid to try to adjust the pH, which, at best, will reach the desired level for only a short period of time before it changes. Additionally, the chlorine will loose much of it’s ability to disinfect and kill of the microorganisms.
To elevate the total alkalinity it is recommended to use sodium bicarbonate. Sodium Bicarbonate should be added slowly, over a period of possibly days. DO NOT add it all at one! The rate at which you should add sodium bicarbonate is figured as follows: 1 pound per 6,500 gallons each four days. An example would be if your pool contained 26,000 gallons, the most you should add each four days would be four pounds. 26,000 divided by 6,500 = 4 pounds total. Use our Chemistry Calculator to determine how much you might need.
To lower total alkalinity you will be using acid in either liquid or dry form. DO NOT disburse the acid into just one part of the pool! Try to distribute it as far from the edge of the pool as you can reach and evenly around the pool. The majority should be placed into the deep end. DO NOT add more than one quart of acid per 12,000 gallons in any given day.
Calcium hardness
Total calcium hardness, relative to your pool means the total mineral content of the water which is made up of calcium, magnesium, iron, manganese and other elements. These elements are already within the water used to fill up your pool. The levels of calcium hardness will elevate through the use of chemicals throughout the year. The ideal specifications for calcium hardness is between 250 to 350 ppm. If the calcium hardness is too low, the water becomes corrosive and results in the etching of the pool's surfaces, metals parts in your system could start to corrode. Running your pool system with a calcium hardness level that is too high is likely to cause rough scale on the interior of your pool underwater surface, “milky” or “cloudy” water and an overall poor performance of you system.
To reduce the Calcium hardness in your pool you will need to remove and replace some of the water. This will take some trial and error experimenting to find out how much water to remove. Try removing about 12” to 18” of water from your pool and replenishing it. If that doe not take care of it, then you should be able to adjust accordingly from there. Low calcium hardness can easily be brought into specifications by adding calcium chloride. DO NOT put all the calcium chloride into the pool at one time! After you determine how much you will need, divide that amount into four equal parts and distribute each of the parts in 8 hour increments.
IMPORTANTFollow all safety guidelines for handling any chlorine product as directed by its manufacturer. |
Total Dissolved Solids
Total dissolved solids, abbreviated as TDS is the measure of the total amount of dissolved solid material in your pool water. TDS is measured in ppm. The highest acceptable reading for TDS is 1500. If your water is testing above this you are probably noticing staining, “milky” or cloudy “water”. If you have tested over 1500 ppm then you need to adjust the TDS by removing and replacing some of the water from the pool. Try removing about 12” to 18” of water from your pool and replenishing it. If that doe not take care of it, then you should be able to adjust accordingly from there.