This also is another factor commonly overlooked, if the stabiliser level is too high in the pool, no amount of Chlorine you add to your pool will change the GREEN pool.

Saltwater pools: Recommended levels are 60-80ppm

Non-Saltwater Pools: Recommended levels are 30-50ppm

And if the pool is in a lot of direct sunlight keep it in the higher end.

Its purpose is to stabilise the chlorine in your pool water, so sanitizer lasts longer. And this where you have a certain amount of FREE chlorine to sanitise your pool

Total Chlorine is the combined chlorine with what is wrapped up with a stabiliser in the pool.

Sample Reading:

• pH 7.2
• Total Alkalinity 42
• Calcium Hardness 225
• BDR 1 drop

Using a Langelier Index Chart, run a straight line across the Total Alkalinity and Calcium Hardness and it shows to have balanced water, a pH of 8.0 is needed. This is too high for the Effective use of Chlorine, so -

Remember that calcium level is the most stable and hardest to move so call it our set point.

Firstly, we consider our Base Demand Test                  

(From BDR chart) of 160 gms of Soda Ash to raise the pH to 7.4 (Note this is Soda Ash).

Secondly, take the Total Alkalinity up and has to be raised from 42 - 130ppm (a 90 mg/l rise) so 90 mg/l in 45 000 liters will need approx 7.0 kg of Bicarbonate(Buffer)

(Note this - 7.0 kg Bicarb)

Remember, when Bicarb is added, it also increases the pH of the water by approximately 0.1 points on the pH scale for each 10 mg/l increase. Therefore, the pH could easily rise to 8.1 when the Bicarb is added so there is NO need to add the Soda Ash.

Now see why the whole treatment must be worked out carefully before beginning. If the Soda Ash had been added a pH of 8.4-8.6 would have occurred.

The Total Alkalinity is correct now but the pH is too high, so - for every 2 points above 7.4, we add .7 Liters of Acid. In this case, the ph is 8.0-8.1 needs 1.7 Litres of acid to correct the pH.

However, another problem arises. The addition of acid also lowers the Total Alkalinity. Checking with the chart, it shows 1.7 liters of acid to a 45000-liter pool lowers the Alkalinity by 22ppm, so, therefore, to raise it initially NOT 90ppm, but 112ppm. So increase the Bicarb to 9.0 kg, not 7.5kg.

The above is the scientifically analyzed pool which can be performed with a Photometer, and when the above is applied to the pool water, Water is balanced.

As the pH is already low and a NEGATIVE imbalance is occurring in the water, add the Bicarb by either mixing with water in a bucket, or straight from the package, but make sure you EVENLY distribute across the pool. And ideally with the pump running to help distribute the Bicarb.

Then approx 1 Hour LATER still whilst pump running adding the acid one liter at a time at one hourly interval.

I realize this in some ways rejects claims and recommendations made out there in regards to the adding of Acid. Their recommendation is adding no more than 1 liter every 24 hours if required, and the two reasons for this:

1. The acid is heavier than water and if poured directly into the pool where there is little water movement, it will settle to the bottom and etch out the plaster/cement and also have an adverse effect on the vinyl liner until it dissipates through the water.
2. They don’t do sufficient testing and analyzing and planning of treatment before going ahead with the treatment.

- Hardy

Because we have used a scientific method of testing, analyzing tests, and planning the treatment before we begin, we know we have an Alkalinity high enough to absorb any excess acid which may be added.

Now if you (Customer) goes home and applies exactly what you have been told to do, then 95% of the time, the water will balance perfectly. The reason we say 95% of the time is because two things can occur in the following hours.

• It may rain, changing the balance.
• Make-up water may be added.

• Debris ie: organic leaf matter and dust from local surroundings.

The only place is the walls and floor of the pool structure. The calcium in the cement and marble render is made up of CALCIUM CARBONATES.

The cement comes out and leaves a rough surface and discolors on the pool surface.

Now let's look at a POSITIVE IMBALANCED pool and its correction.

• Pool size - 45000 Litre.
• pH - 7.6
• Total Alkalinity - 540ppm
• Calcium Hardness - 380ppm
• A.D.R - 1 drop

We have to drop 460ppm so check the chart and it says seven liters per 100ppm required to drop. That is 32 Liters required to give us 80 ppm. CRAZY YOU SAY, No stop thinking about what was said, “IT ALL DEPENDS”.

In this pool you would find that the first 10 - 15 Litres would create NO pH change at all only on the last 5 liters would it begin to change the pH. The pH change would end up in the range of 6.0-6.5 and would be adjusted back up by doing another pH test and then the Base Demand Test and using a small amount of Soda Ash as indicated of the chart, and the figures would then end up like this:

• pH 7.4 (Spot On)
• Total Alkalinity 80 ppm (Good)
• Calcium Hardness 380ppm (Spot On)
• A Balanced Combination.

And to give you another example which should not be as expensive as the above scenario but still as tricky as the above and how you would approach a pool with the following readings.

• pH 7.6
• Total Alkalinity 540ppm
• Calcium Hardness 380ppm
•  Acid Demand ADR 1. Drop

Using the Langelier Index Chart see that the closer you can move both the Calcium and Total Alkalinity to the 180ppm figure the easier it will be to balance.

You will also notice that there is a very POSITIVE imbalance in the pool, thus this could be CLOUDY water.

So instead of fighting the water, let’s help the water do what it wants to do which is rid of the dissolved solids in it.

Do the pH test again to check it is 7.6 and then a Base demand test drop by drop until an 8.3 reading is obtained. See it takes 2 Drops. Referring to the Chart it tells us 330gms of Soda Ash are needed to increase the pH to 8.3.

When the Soda Ash is Added an even greater imbalance is created and the water drives more solids out of solution into suspension thus forming dense clouding in the pool.

Now using a non pH Clarifier preferably anionic polymer to flocculate the suspended Calcium and bicarbonates.

When these settle to the bottom of the pool vacuum the pool to WASTE. ( Note: Don’t leave these salts on the floor too long in a marbled pool)

Take a scientific approach and execution in the tests and treatment. Always follow the system:

1. Test
2. Analyse
3. Plan Treatment
4. Treat.

Remember, IT ALL DEPENDS upon the three factors - pH, Total Alkalinity and Calcium Hardness and three minor factors temperature, TDS(Total Dissolved Solids), and stabilizer.

As I have tried to explain and mention, there are no real levels: as long as they are balanced then the water is easy to manage.

Too low TDS will lead to problems in the filtration system. It has been discovered that although the filters remove only suspended solids NOT dissolved solids, the amount and the size of a certain suspended matter is related to the TDS, of the water containing it. As the water is lowered in TDS the particles which would normally adhere together and be large enough to be removed by the filtration system, stay apart and pass through, especially with Sand filters.

This has been proven where a filter would not remove the colour from pool water at a TDS of 50ppm, but when increased to 550ppm without chlorination the colour was reasonably removed.

Low TDS will lead to a light green tinge appearing in the pool water as there is no body in the water to reflect the light and thus give the water a BLUE look colour. By increasing the TDS above 150-200ppm the colour will be removed even without filtration.

Chlorine usually removes colour by oxidizing the particles which are causing the colour and thus by eliminating to form salt in the water which in turn increases the TDS. Now if the water is green through lack of TDS or lack of body also called the lack of the ability of the water to reflect, then the chlorine cannot be expected to work on something which does not exist. ONLY if there is some mineral or organic matter dissolved or suspended in water can the chlorine remove the colour to achieve this TDS levels must be in the range of 500-800ppm.

Swimming Pools are damp and warm by nature, a breeding ground for bacteria, algae, and many other organic compounds.

Not all are harmful, but those which are, usually outnumber those unharmful ones.

Whilst swimming a lot of bacteria, dirt, germs, body oils, skin, and other body secretions into the pool water called either phosphate or pollution and when this increases in the water it tends to change the colour, taste, and an unpleasant odor, and all this can be removed with chlorination.

When Chlorine is added to the pool, it reacts with ammonia compounds which are present in the form of urine and body perspiration and forms what are known as Chloramines, which are also removed with more Chlorine.

Calcium Hypochlorite would be the largest being used in Australia, and when this product is added to water we have the following reaction:

Calcium Hypochlorite(Dry)   Water   Hypochlorous Acid Calcium Hydroxide

Ca(OCl)+H20 =2HOCl + Ca(OH)2

So when they combine, there is Hypochlorous acid formed and this is the major ingredient in killing the bacteria, algae and oxidizing the organic matter, removal of colour and taste, and the destruction of what are called chloramines. In this process at the same time a small amount of Calcium Hydroxide is formed which over some time will gradually raise the pH of the water; thus the need to test for pH occasionally and adjust using acid.

Most Calcium Hypochlorite sold and used today contains a strength varying from 60-80% Chlorine which forms into hypochlorous acid. This acid is the FREE available chlorine. Therefore, it is needed to be known what percentage of available chlorine is in the Chlorine compound being used. There is one other reaction happening in the pool known as ionization, this occurs when all compounds are mixed in the water as it does when hypochlorous acid is formed.

The HOCL breaks up to form H+ or positive hydrogen ions and OCL or negative hypochlorite ions. This is also a reversible reaction.

All the hypochlorous Acid we have made in that reaction may be no more. It may have become what we call in the industry “disassociated”. And chlorine in a “disassociated” form, is as good as useless. The best and most practical way to control this problem is by controlling the pH.

The lower the pH the greater the amount of Hypochlorous acid in an undissociated form and the less hypochlorite ion. The higher the pH, the less hypochlorous acid and the greater hypochlorite ions.

Now water needs to be at a comfortable pH for people to swim in ranging from 7.2-7.6.

There is now a supply of available hypochlorous acid ranging from approx, 60% at 7.2 to 40% at 7.6. This the most that can be obtained and the best must be done with it. Work on the basis that efficient chlorination is to obtain the most amount of hypochlorous acid possible at a time when there will be the least reaction with sunlight.

As mentioned, chlorine in the hypochlorous acid form breaks down bacteria and algae. It does this by eating into the very basis of any living organism- it’s enzymes. Once the enzymes in the living substance are destroyed, then the organism can no longer live; so bacteria and algae die. The other problem which can occur with algae and that is dead algae forms a coating over the live algae underneath and STOPS any further action from the chlorine.

The best way to explain this is to talk about a pool that has continual chlorination such as a council pool.

When the pool is opened in the morning, the water is crystal clear, no algae, bacteria or objectionable compounds in the water-just as much hypochlorous acid as the pH will permit. In the process of people swimming a lot of pollution is brought into the pool in the form of perspiration, urine, and body excretions all contain strong compounds such as ammonia. The ammonia combines with chlorine to form what we call monochloramines. Once there is enough ammonia, it can react to dichloramines and trichloramine.

It is the nitrogen trichloride along with the di and mono chloramines which give people sore eyes, smell and taste of chlorine in pools. As more people swim, more ammonia is introduced and thus more chloramines. Chlorine does a tremendous job breaking these chloramines down and getting rid of all the above nasties as long as there is ENOUGH FREE CHLORINE present and available.

A public pool like above has continuous chlorination and therefore continual build up and breakdown of chloramines.

A private Home Swimming pool, has a large build up of nitrogenous compounds or ammonia during the day when people are using the pool. As soon as chlorine is introduced at night, there will be extremely fast growth of chloramines as the free chlorine combines with the ammonia compounds.

Let me define the two products being discussed:

• Hypochlorous acid which is known as Free Available Chlorine. This means it is free to work when and as required to kill bacteria and algae, oxidize organic material and breakdown chlorine or chloramine compounds. This Chlorine is known as FAC(Free available chlorine) and it is the most valuable asset in treating your pool water.
• Chloramines, due to the large amount of chlorine they contain, have a very weak effect(but some effect) on killing bacteria, algae and oxidizing organic material. This chlorine which is not free to work as it please, is known as COMBINED AVAILABLE CHLORINE or CAC. As chlorine, it is basically useless and affects the eyes, taste and smell and uses the FAC(Free available chlorine) instead of leaving it for more important tasks.
  
  

The above two products give us the “Total Available Chlorine” or TAC- the sum of the FAC and combined chlorines. The test we should do on the pools water are most easily done on FAC(Free available chlorine) and TAC(Total available chlorine) subtract the FAC from the TAC to receive a measure on the CAC(Combined available chlorine)

Breakpoint chlorination means chlorinating to a level whereby when testing the FAC (Free avail Chlor) and the TAC(total avail Chlor) at a future time, the exact same answers for both tests. This means that however much chlorine was added, it is enough to kill all bacteria and algae, oxidize all the organic materials and destroy all chloramines which would have been formed when added, only then will it be considered water sfe and clean enough for you to swim in.

How to achieve BREAKPOINT CHLORINATION.

How much chlorine is needed to overcome all the pollution in the water. For this, an initial 5.0 mg/l chlorine level is needed in the water. Remember there is a disadvantage because everyone has been swimming in the pool all day and there is no chlorine, so one can not do a chlorine test to check the CAC (Combined Avail Chlor) to tell how much chlorine is needed to break the CAC down.

All that can be done is to correct the pH to 7.2-7.6 level and add the required amount of chlorine for 5 mg/l level as per chart.

Mg/l(definition)- mg/l means the number of milligrams of a product in a liter or kilogram of water - thus 5 mg/l means 5 milligrams in one liter or 0.225 kg in 45,000 liters.

However, this is if the product is 100% pure compound and that being used is only 65%, so add (225 gms divided by 0.65) being 350 grams.

When the chlorinator is running at 80% there should be a constant mist coming off the salt cell, and check to see the plates are not worn.

People forget they must still check and correct the pH level at least once a week and Total Alkalinity and calcium hardness monthly, and ensure the out-put is correct.

When an automatic dosage machine be it a chlorinator or liquid dosing system feeding into the piping, take care to ensure the return to the pool inlets(Return) are min 300mm-450mm below water level, the deeper the better, and turned towards the base of the pool to force heavily chlorinated water to the main body of water before it has a chance to dissipate into the air.

 And with any Sanitisation system, the best time to run them as much as possible is at NIGHT when there is NO sun to dissipate the chlorine as it enters the pool.

When using Calcium Hypochlorite(Hypo) or granular chlorines, the only time to have a fixed chlorine level to work to and for, is when doing an early morning test-thus one must dose accordingly.

 A test of 0.5ppm of FAC(Free available chlorine) with a CAC (Combined available chlorine) of 0.0 is acceptable, as mentioned earlier there must be no CAC at this test time but still have a FAC. Then the chlorine has done its work in killing all bacteria and oxidizing organic compounds and removed all the CAC. NOW you have perfect water to swim in.

When Stabilised Chlorine is used, the FAC must be higher at all times because it only needs the introduction of a small amount of pollution and there is no more FAC. Admittedly there will be more FAC building up during the day but as there is no shock dosing nightly, try to stay ahead.

If working with a 30ppm Cyanuric(Stabilizer) Level, then run a minimum FAC of 1.0-1.5ppm. The higher the Stabilizer reading the higher minimum FAC, But remember the higher the Stabilizer generally also increases the TDS(Total Dissolved Solids) which will impede the processes of the chlorine.

Algae are chlorophyll containing plants without true roots and without distinction of leaves or stems.

Algae needs energy from the sun to convert inorganic matter into their own protoplasm. They do not require oxygen to live: they actually split up water to produce oxygen. This is why they are so good in harbouring aerobic bacteria which live on the oxygen produced by algae.

Also, undissolved chemical deposits such as Calcium deposits on walls and floors of pools give growth areas to algae.

Algae in the swimming pool causes staining and slippery conditions and shows that the chlorination of the pool is defective. Any pool which has the correct pH, water balance and an adequate amount of FAC(Free avail Chlor) will NOT contain Algae. Algae growths will always have a greater chance of growing in water with a higher mineral content or high Total dissolved solids level. In the presence of sunlight the inorganic mineral compounds dissolved in the water become the chemical building blocks with which the algae make the cells to form their bodies.

Algae is not healthy and also very unsightly. Its presence means the pool has been neglected, many people claim that even when they keep good chlorine levels (according to their test kit which may only be giving TAC, and their pH is correct, they still have algae.! This is usually too good to be true, as mentioned before, it is rare to find algae in a pool which does not have deposits, so if it does have deposits that means the pool has or is not balanced for a while.