Pool & Spa Maintenance

Why Sanitise?

With decades of experience in building swimming pools, Mainstream Pools stresses the importance of regular pool and spa maintenance with the long term benefit being that you and your family can continue to enjoy the pool or spa for years to come.


Pool/Spa water is easily contaminated with algae and bacteria from a variety of sources including wind; top-up water, pets and users.


Untreated or improperly treated pool/spa water can be a health threat. Properly chemically balanced and sanitized water on the other hand, will provide a healthy and visually appealing environment for you, your family and friends.


Controlling these influences is an ongoing requirement and involves chemically balancing the water to ensure it is neutral to users, the pool/spa itself, and the pool/spa equipment.


Regular testing and balancing of your water, sanitizing the water to oxidize contaminants and filtering the water to remove the oxidised contaminants takes little time but ensues that all is well with the pool/spa water.


The following sections deal with each of these requirements and form an easy program for regular pool and spa maintenance.

Water Balance

Your swimming pool/spa is a water Container and the water it contains must be suitable for both:

  • The user and
  • The container


Balanced water means that its chemical demands are being met.


If the chemical levels are too low, the water will aggressively seek the chemicals and minerals it needs by attacking the pool/spa surface and equipment. This may lead to severe corrosion problems. At the other end of the scale, high chemical levels will precipitate from water and form scale on the pool/spa surface and associated equipment etc.


Out of balance water can cause expensive damage to the pool/spa and may also inhibit the sanitising process


In simple terms, a scientific water balance program suggest that the pool/spa owner should balance the following variables:

  • pH
  • Total Alkalinity
  • Calcium Hardness


pH is a measure of how acidic or alkaline the water is, and, the pH scale ranges from 0 to 14, with 7 being neutral. Values below 7 are acidic, and, values above 7 are alkaline.


With pool water we are seeking a pH balance suitable to the safe and healthy human use of the pool/spa, together with the sanitizer being used.


Topping up your pool/spa , rain, heavy bathing loads, and chemical additions can all change the pH level of your pool/spa water.


pH must be kept within the Recommended Ranges, as if it is too high or too low, it may:

  • Create swimmer discomfort (itchy skin, red eyes etc.), and/or
  • Interfere with the sterilising action of you water sanitiser


pH is the most important aspect of you pool/spa maintenance program

The effect of pH on Chlorine

Effective sanitizing relies on pH values. Therefore, sanitizer and pH levels should be the measurements you check and adjust most often.


Regardless of the chlorine type or chlorination process you use, any pH drift above the “Recommended Range” (7.2 to 7.6 or 6.8 to 7.2 for fibreglass pools) will inhibit the sanitizing effect of your chlorine.


For example, a pH level of 8.2 would mean only about 16% of your chlorine would be available to sanitise the water, which means that you would have to add more than 5 times as much chlorine to achieve the same sanitizing effect. When the pH is lower than 7.0, the chlorine becomes extremely active and is rapidly consumed.

Total Alkalinity (TA)

This is the measure of the bicarbonates, carbonates and hydroxides in your water. The Operational Range is 60 to 200 parts per million (ppm).


Your NSPI Accredited Specialist will advise you of the Recommended Levels to suit your pool/spa and its environment.


Low TA will lead to erosion of the inner surface in concrete and painted pools/spas as the water takes the chemicals it needs from the surfaces.


Low levels will also cause the pH levels to be very unstable with small additions of chemicals resulting in major shifts in the pH values. This is sometimes known as “pH bounce”.


Your Total Alkalinity (TA), can be changed in the following ways;

  • Adding “buffer” (ie: bicarbonate of soda), which is used to RAISE the TA
  • Adding “acid” to the water to lower pH, will also LOWER the TA
  • Adding “Top-up” water may change the TA (depending on the quantity and the TA of the top-up water itself).

The Interconnection between pH and Total Alkalinity

From the last section, it can be seen that acids will lower both pH and TA, as there is an interconnection between these two chemical components, and because of this, they need to be always adjusted together.


The levels you are seeking to maintain are:

  • A pH of 7.2 to 7.6 (or 6.8 to 7.2 in a fiberglass pool), and
  • A Total Alkalinity of about 100ppm (or, as directed by you SPASA Member).


Let’s have a look at the interconnection, and assume that the pH is OK but the TA is low.

  • To raise the level of the TA, you must add, “Buffer” (Sodium Bicarbonate) at the required rate. However, “Buffer” is an alkali, and will also raise pH, and “Acid” (used to lower pH), also lowers TA.


The idea is to raise TA artificially high, so that when the “acid” is added (to lower the pH to the recommended range), the TA is also reduced.


Remember – do not try to do it all in one go – allow 6 to 8 hours between adjustments, testing each time.


Two “acid” types are used to lower pH. One is Hydrochloric Acid (Spirits of Salts), and the other is Sodium Bisulphate. Both of which will effectively lower the pH and TA.


Check with your NSPI Accredited Specialist as to which type is most suitable for you and your pool/spa. If using Hydrochloric Acid to lower the pH, it is vital that it be diluted (one part of acid to ten parts of water), prior to adding to the water.


Note that the filler should be running during these additions, and, for about one hour afterwards to ensure adequate mixing.


No other type of “acid” should ever be used for pH or TA adjustments.

Calcium Hardness

In simple terms, measure the amount of dissolved calcium in your pool/spa water. The desired range is 80 to 500 ppm; however, you should consult with your NSPI Accredited Specialist for the specific requirements of your particular pool/spa finish, water supply, environment and equipment.


Both Total Alkalinity and Calcium Hardness need to be brought into balance, if not;

  • Low levels will mean that the water is corrosive to the pool and or equipment, and
  • High levels will lead to the scale formation on the pool equipment


A normal water test kit cannot perform measurement of Calcium Hardness, and we would suggest that a water sample be taken each month to an NSPI Accredited Specialist for testing. A rough rule of thumb in areas where calcium levels are not naturally high is that testing annually will suffice after the initial adjustment.


The only exception to this is; if you use Calcium Hypochlorite (65% Chlorine) to sanitise your water, and, depending upon the method used – this chemical can quickly raise Calcium Hardness levels, and may require more frequent testing and adjustment.


Chlorine is the most commonly used water sanitizer in the world, and, there are many forms of this highly effective product, including;

  • Cranular Chlorine (calcium hypochlorite – 65% active)
  • Liquid Chlorine (sodium hypochlorite – 10/15% active)
  • Sablised Chlorine (in two forms);
  • “Dichlor” granular chlorine (approx. 60% active), and
  • “Trichlor” slow dissolving tablets (approx. 905 active), and
  • Salt Water Chlorinators (electronic units which produce chlorine by the electrolysis of salt in the pool water)


Whatever form of chlorination you use, for it to work efficiently, the pH must be within the Recommended Range.


Queensland Health recommend chlorine levels be maintained at;

  • At least one (1) part per million of Free Available Chlorine in an unstabilised pool/spa, or
  • A least two (2) parts per million Free Available Chlorine in a stabilised pool/spa


Free Available Chlorine can be tested with a test kit.


Utlra-violet light attacks chlorine, and “stabilizing” the water involves adding the chemical Cyanuric Acid, which reduced the amount of chlorine destroyed by sunlight. Up to 5 parts per million of free available chlorine can be destroyed in three hours of strong sunlight.


For health and financial reasons, it is important to overcome this effect as much as possible, and so stabilizing the water is strongly recommended.


For the initial stabilizing of a new pool/spa, Cyanuric Acid should be added to achieve the recommended level of 30 to 50 parts per million.


Stabiliser is lost through splash-outs and by backwashing the filter, and, will need to be replaced regularly, especially during the summer season. To do this, it is necessary to first test for the residual levels in the water.


NSPI Accredited Specialists can do this testing from a water sample, and, based on your pool/spa volume, can recommend how much stabilizer to add.


As you only need stabilizer occasionally, fix the correct level at the beginning of the summer season and then check it every few months during the year. Naturally, if you have to pump out the water, or lose a lot through slash-outs or backwashing, more frequent testing and adjustments may be required.

Any Chemical Additions

As a general rule, you are far better off adding small amounts of chemicals whilst running the filter, and testing the effects after several hours. Attempting large chemical changes by adding large amounts of chemicals can result in big problems.

The Filtration Process

So far, the treatments have dealt with the chemical destruction of water contaminants. “Filtration” is the physical removal of neutralized contaminants (chemical and human wastes), together with the insoluble particles from the water.


Daily filtration cycles should be in the order of 6 to 8 hours (depending on the size of the system installed), to ensure that at least (1) one “turnover” is achieved (that is, as a minimum, the equivalent litreage of the pool/spa is filtered each 8 hours).


Additionally, the filter should be running during periods of use (and for a short time after), to skim body oil from the water, and, to add some chlorine (if an automatic chlorinator is fitted).


Remember that when the pool/spa is being used, there is a high chlorine demand, due to the user contamination of the water.

The Filtration System

While filtration system may differ in regard to their type, they will all have the following basic features:

  • A Skimmer into which the inflow carries surface debris (leaves, oil, dust etc), into the start of the filtration system,
  • An initial Leaf Basket in the skimmer to trap leaves and large debris, before the water is suck through the pump,
  • A Secondary Basket in the hair and lint pot, in front of the pump,
  • A circulating Pump,
  • A Filter which physically removes solids from the water, and
  • Pipework through which the clean water is returned to the pool.



To prevent rubbish inhibiting the water flow and causing pump starvation), these items need to be checked and cleaned regularly.

Types of Filters

All filtration relies on removing solid matter from the water as it is pumped through the filtration system.


There are three popular types of filtration systems currently in use in Queensland:

  • Diatomaceous Earth (or DE Filter)
  • Sand Filter
  • Cartridge Filter


All three types have high flow characteristics, and are highly efficient. However, they all require cleaning to remove the entrapped solids, and failure to clean filters (as required) will result in reduced filtration flow, because of the accumulated debris blocking the filter medium.


Regular cleaning (as indicated by the pressure gauge) is essential. Failure to clean filters can also cause an increase in pressure within the filter tank, which will reduce the life expectancy of the unit.


Cleaning methods will depend upon the filter type. Both DE & Sand Filters can be “backwashed” (which is to reverse the flow of water through the filter tank, and flush the rubbish to waste).


Cartridge Filters require hosing down, and soak in the correct cartridge cleaning fluid.


Regular cleaning of a filter will provide benefits in terms of better water flows for filtration & vacuuming, and, better chlorination, and, better circulation within the pool, due to the increase flow rate.


In addition to this regular cleaning, periodic service of the filter is recommended to remove any build up of grease and scale. This can be arranged through your NSPO Accredited Specialist.

Automatic Chlorination Systems

The cleaning and maintenance of these automatic system is most important, to ensure that they continue to function up to their designed standards of performance.


In its normal use, a Salt Water Chlorinator (due to the electrolytic action which converts salt to chlorine within the cell) attracts calcium (and other contaminants in the water), which adheres to the cell mesh and which will interfere with the chlorine production of the unit, and eventually reduce the expected life of the unit.


Check and clean the cell, only in accordance with the manufacturer’s recommendations.

Safety Rules

NEVER MIX CHEMICALS – this could lead to an extremely violent reaction (explosion!), and/or the production of Toxic Fumes. Do not even use the same bucket for diluting different chemical, as; even different chlorides can react violently when mixed together.


When transporting chemical in your car, do so in a manner that prevents them mixing in the event of a spillage or an accident, and, secure all containers firmly.


Store chemicals so that any accidental breakage or leakage cannot cause a mixing of pool chemicals, or, a mixing of a pool chemical with any other stored substance.


Some pool chemicals can cause nasty burns or be poisonous, and you should always store them securely away from the children or pets can get at them. You should also use protective gloves, clothing and eyeglasses when handling.


Always add the chemical to a bucket containing water – not the other way around. To add water to a chemical is potentially dangerous. Dilute all pool chemicals with water by at least 1:8 prior to adding to the pool.


Gave the filter running when you are adding chemicals to the pool water to ensure proper mixing and distribution.


Always read the instruction on the labels of the pool chemicals and other products – and, follow them carefully.

General Tips

Pool Water Samples

When you take a pool water sample for testing to your NSPI Accredited Specialist, make sure that the container being used does not contaminate the sample.


Use a well-washed glass jar, fill to the top and cover with 2 or 3 layers of plastic wrap before screwing on the lid. Under no circumstances should plastic fruit juice or cordial bottles used.


Some NSPI Accredited Specialists will provide special sample container designed for this use.


Transport the sample to the test point promptly. Try not to allow the sample to heat up, as this may change the chemical levels, and give a misleading result.

Test Kits

Test Kits should perform at least 3 functions, which are;

  • Sanitizer (Chlorine, Bromine or Other)
  • pH, and
  • Total Alkalinity.


Test kits may either be the colour drop type, or the 3 way “dip stick” type.


In remote areas where access to a water testing facility is impractical, other supplementary test kits are available to test calcium hardness, cyanuric acid, and salt.


All Test Kits should be stored in cool conditions, and not exposes to sunlight.


Liquid reagents should be replaced at the beginning of each swimming season.

Future work around the Pool

  • All work around the Pool structure must be separated by a flexible compression barrier
  • Adequate drainage in surrounding gardens, landscaping and walkways within 3m of the waters edge must be provided to ensure that the pool structure remains dry.

Landscaping & Sub-Soil Drainage

Australian Standard 1839 contains recommendation regarding sub-soil drainage for fiberglass and other pools, except in areas with highly permeable soils.


Where such drainage systems have been installed and additional site works are planned, it is recommended that contact first be establish with the Pool Builder to ensure that the drainage system will not be adversely affected.


Remember that hydrostatic pressure from ground water can affect fiberglass and other pools.

Use of Standpipe

Fibreglass pools may also have a standpipe installed as part of the sub-soil drainage system, which allows for measurement of the height of the underground water table. Check it regularly to ensure it remains free of water.

Should I Empty My Pool?

Swimming Spas and Pools (as a general rule), should not be emptied on a regular basis.


However, if you think your pool or spa needs to be emptied for whatever reason, check with your SPASA Member first, as emptying it without consultation with the Pool Builder may also void that builder’s warranties.


Most problems can be treated without the need to empty a pool, and exposure to the sun and other elements, may lead to additional remedial work being required.


If you live in an area with a high water table you should take particular care, and not simply reply on the hydrostatic relief valve.

What Happens in Winter?

It is important to note that whilst the pool maintenance requirements may lessen during the non-swimming months, some maintenance will always be needed to your pool. Earlier section in this booklet deal with specific pool maintenance.


Do not allow your pool to deteriorate into a “swap” during the winter months by thinking that you can save on the small amounts of chemicals and electricity required, as, the damage done to a pool and/or the cost required to restore the pool back to the swimming condition, will seriously outweigh any savings made.


To keep the pool and associated equipment in good working order during the winter, the system running time can be reduced (4-6 hours a day).


Addition of a “Winteriser” (Algacides) may also be consider when pool water temperature reduces to 20 degrees C, or less.


Check the skimmer basket and pump lint pot regularly, and keep clean & clear (as a reduced water flow may cause “cavitation” and damage the pump), and periodically check water balances.


For further and more detailed information, you may wish to purchase:
“Private Swimming Pools – Water Quality” (Australian Standard 3633) from the local Standards Australia Office, or “Pool & Spa Owners Guide” from Choice Books (Australian Consumers’ Association)

Read our blog to find out more!

Glossary of Terms

Bromine ­– a form of sanitizer most commonly used in spas because of its tolerance of hot water.


Buffer – an alternative name for Sodium Bicarbonate, which is use to raise Total Alkalinitity. Acid should be used to lower pH, but will also lower Total Alkalinity to some degree. The only acids to be used are Hyrochloric Acid and Sodium Bisulphate.


Algaecides – available in many forms and types. These products are s supplement to you santiser, and are intended to kill all forms of algae. Note: check with your NSPI Accredited Specialist prior to purchase for compatibility with your pool maintenance systems.


Alkali – a chemical with a pH above 7 (eg: Soda Ash and Sodium Bicarbonate). Note that Soda Ash will mostly affect the pH, while Sodium Dicarbonate will have a major influence on raise the Total Alkalinity.


Alkalinity – a minimum level of 60 parts per million is recommended as this “buffers” the pH against undue sensitivity to other chemical additions.


Backwashing – the process used to clean Sand & DE filters by reversing the water flow to flush out accumulated dirt.


Calcium Hardness – the amount of dissolved calcium in the pool water.


Calcium Balances – a composite term covering those aspects of water which should be adjusted to achieve water suitable for swimmers, the sanitisers in use, the pool surface, and the associated equipment. Pool water is chemically balanced when the pH, Total Alkalinity and Calcium Hardness levels are all within the recommended ranges.


Chlorinator – normally in one of three forms:

  1. Salt Water Chlorinator – a unit that manufactures chlorine through the electrolytic conversion of salt. Chlorine levels will depend upon several variable, including running time of the unit,
  2. Liquid Chlorine Feeder – a device that feeds liquid chlorine into the pool water. Normally integrated with the filtration cycles, these devices have electronic control on chlorine, or
  3. Erosion Feeder – a device containing solid Trichlor tablets, which controls the rate of chlorine addition through a manual valve that varies the water flow over the tablets.


Chlorine – a pool sanitisers that oxidises contaminants in swimming pool water. It is pH dependent. There are many different types of Chlorine available – check with an NSPI Accredited Specialist for the most suitable for your pool. Note: the use of Liquid Chorine in aboveground pools may affect the Manufacture’s warranty.


Combines Chlorine – chlorine that has combined with nitrogen based compounds to form Chloramines. Associated with a very strong chlorine like smell, this compound is a poor sanitiser and indicates the need for more chlorine (see super chlorinate).


Filter – a device to remove oxidised material and debris from the pool water. The main types of filters used in Queensland are DE (Diatomaceous Earth), SAND and CARTRIDGE.


Flow Rate – the rate at which your water is pumped through the filtration system (Litres per hours)


Free Available Chlorine – that portion of chlorine in the pool water available to oxidise contaminants as opposed to “Combined Chlorine” or “Total Chlorine”.


Hair and Lint Pot – that section of the circulating pump that contains the secondary strainer basket for the filtration system. It requires regular cleaning.


NSPI Accredited Specialist – a swimming pool and spa industry expert who has under taken training and successfully completed a National Swimming Pool Institute Course. To find your Local Accredited Specialist go to www.nspi.com.au


pH – a measure of the alkalinity (above 7.0) of pool water. The only acid, which should be used to lower pH are Hydrochloric Acid or Sodium Bisulphate.


Pump – the device that circulates the water through the filtration, heating/cooling and chlorination systems and within the pool itself.


Saltwater Chlorinator – is a type of chlorinator that produces chlorine from saltwater by means of electrolysis.


Sanitiser – a range of chemicals used to control bacteria in pool water.


Skimmer Box – the suction point in the side of the pool where water is drawn into the filtration system. An important part of this fixture is the floating weir flap which serves two functions; the first is to take advantage of the surface tension and cause the top layer of the water to flow into the skimmer, removing debris floating on the water surface, and, secondly, the flap closes when the pump is not running, preventing the debris from floating back into the pool. Cleaning the skimmer basket is an important part of pool maintenance.


SPASA – means the Swimming Pool 7 Spa Association of Queensland.


Stabiliser – Cyanuric Acid is used to screen the pool water from the sun’s UV radiation that attacks the chlorine. The use of this produce is recommended for all chlorinated outdoor pools. Regular checking and maintenance during the swimming season is recommended. Stabiliser should not be used in indoor pools.


Super Chlorination – the addition of chlorine, usually calcium hypochlorite at the rate of 100 grams per 10,000 litres of pool water. It performs three functions;

  1. The destruction of compounds such as chloramines,
  2. The destruction of harmful bacteria, and
  3. The destruction of algae spores resistant to normal chlorine levels.


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