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Innovative designs and a focus on quality, make Australia a world leader in pool & spa filtration.
The task of the filtration system is to pump water from the pool, pass it through some form of filter medium and return it to the pool in pristine condition.
SAND FILTERS
By far the most popular option, these units force pool water through a tank filled with finely graded sand. As it passes through, the impurities attach themselves to the grains of sand. The larger particles are trapped at the surface of the sand bed and the finest particles are collected deep inside the bed where the grains are more tightly packed.
BACKWASHING
Over time, the accumulated impurities will restrict the flow through the filter and the pressure gauge will indicate backwashing is required. This process can be controlled by the filter’s multiport valve. Once set to ‘backwash’, this valve will reverse the water flow and send the unwanted particles down the ‘waste’ line.
After a minute or so, the water should be clear again. Usually a sight glass will allow you to monitor the process. Some filters even allow for automatic backwashing and this ensures the filter is always at peak efficiency, even if it has been left unattended for a prolonged period.
DIATOMACEOUS EARTH (DE) FILTERS
The water clarity achieved by a DE filter is quite remarkable, but there is a downside.
DE filters are both more expensive to buy and more work to maintain.
The DE medium is actually fossilised diatoms, which are not unlike coral. When crushed, they create a very fine powder and each grain has microscopic holes running through it to trap even the finest particles. It’s added to the filter by mixing with water in a bucket and pouring the slurry into the skimmer box.
Once inside the filter, dacron pads, septums or tubes trap the DE material to form layers or cakes of DE. These cakes then begin to trap the particles in the water flowing through.
Backwashing is the same as it is for sand filters but here the DE material is also flushed away and a new slurry needs to be added after the backwashing is complete. For the system to operate efficiently, the septums will also need to be removed and hosed down once or twice a year. Pads can clog at times and using granular chlorine as a sanitiser can cause a calcium layer to build up on the pads. So maintenance is greater but the brilliant end result may be well worth it.
CARTRIDGE FILTERS
As the name implies, these filters use a man-made cartridge as the filter medium. Folded into the tank like a concertina, the filter material has a surprisingly large surface area. The principle does not involve a backwash line so they don’t need connection to the sewer or waste line. This makes them ideal for spas and areas where disposal of waste is an issue.
Cartridge filters can be installed before the pump, and if necessary inside an oversized skimmer box when space is restricted. Cleaning is simply a matter of removing the cartridge and hosing it off, although having a second cartridge to use while the clogged unit is soaking overnight in a cartridge cleaning solution is recommended.
There are many factors to consider when selecting the type of filter that’s best for your installation. It is always wise to seek the advice of a SPASA Victoria Pool Builder or Pool Shop Member.
Sky-blue gas? Heavy metal? There’s more than one way to sanitise a pool or spa
Ozone is a sky-blue gas formed naturally by the action of the sun’s ultraviolet rays or when a large electrical discharge, like lightning, passes through oxygen. It is a relatively unstable, highly toxic gas which decomposes to re-form oxygen and is very effective against bacteria.
TASTELESS AND ODOURLESS OZONE
Used for many years in the USA and Europe, ozone is the standard purifier in both water bottling plants and in pools approved by the Olympic Federation.
One of the most effective disinfectants and oxidisers, ozone starts killing bacteria and oxidising organic waste as soon as it is injected into the circulation stream.
TOXIC TO MORE THAN BACTERIA
All traces of ozone must be consumed or removed prior to it reaching the pool, so small amounts of residual sanitiser like chlorine or bromine must be used to provide continuous protection within the pool.
If using ozone with chlorine, follow the manufacturer’s recommendations on maintaining pH. If using it with bromine, the oxidising power of ozone will regenerate the inactive bromine, reducing the consumption of bromine product.
Due to its instability, ozone remains in the water for only a short time and has no effect on pH or water balance. Nor does it contribute to Total Dissolved Solids. It can even reduce the need for shock dosing.
OZONE GENERATORS
Recent developments in technology have enabled manufacturers to produce smaller, more economical ozone generators more suited to domestic pools and spas. These units produce the gas in two ways. Passing air over an ultra violet light source or through a Corona Discharge chamber will generate ozone.
The gas concentration produced in both systems can vary, so follow the manufacturer’s recommendations and select the unit most suited to your pool or spa.
IONISING SILVER AND COPPER
Ancient Greeks found that water kept in silver containers mysteriously purified, and algae didn’t grow in copper water pots. In the late 19th Century, water was passed through various porous materials impregnated with silver, creating positive ions and purifying it.
ELECTRIC HEAVY METAL
Today, an ion-generating device can be installed in the circulation system. It’s made up of an electrode assembly (a copper electrode and a silver electrode) and the electronic control unit that supplies an electric current to the electrodes. Electrolysis then passes either silver or copper ions into the water where the silver disinfects and the copper prevents algae growth.
PURIFICATION AND BALANCE
Electrolysis of metals does purify but it does not chemically balance the water. See SPASA Victoria Fact Sheet 5 to correctly balance the water. Silver and copper residual levels can be measured, however the registration authorities require maintaining a chlorine or chlorine-free disinfectant residual as well.
The metal ions kill algae and bacteria but they do not oxidise organic waste. It is therefore necessary to ‘shock treat’ or ‘super chlorinate’ the pool to oxidise any build up of organic waste and maintain disinfecting action.
Note that dissolved metals may stain a pool or spa, or discolour the water. Always keep the copper and silver residual levels within the manufactuer’s recommendations.
Increase your swimming season and the value of your investment
The ideal pool temperature is around 25 to 28 degrees celsius, but this is very rarely achieved naturally.
The average unheated water temperature in most of Victoria is 13 degrees and only reaches 18 – 20 degrees for short periods during the swimming season. Gas heating can quickly and efficiently heat your pool to a comfortable temperature at any time.
Your swimming season can be as long as you like, and the value gained from your substantial investment in your pool will be much greater.
Increased availability of natural gas and LPG has made it a popular form of swimming pool heating. It’s always available and can be closely regulated so it’s ideal for use on both pools and spas.
HEATER RATING (SIZING)
The gas energy consumed by a gas heater is measured in Megajoules (MJ) and the energy output rating is in Kilowatts (kW).
Smaller heaters are in the range of 60 to 100MJ and range through 250 up to 500MJ. The output ranges from 15 to 110kW.
WHAT SIZE HEATER SHOULD YOU CHOOSE?
Selecting the right heater depends on a number of factors. You need to consider the size of your pool or spa, the maximum temperature you would like to reach and how long you are willing to wait for it to heat up.
If you have a pool and spa combination, remember to consider both when deciding. Spas usually need to be heated more quickly and to a much higher temperature than pools, so select a heater with this in mind. If only a pool is being heated, it is not as critical to heat it quickly, so perhaps a smaller heater could be considered.
CONTROLS
All gas heaters are fitted with thermostatic controls. These range from simple mechanical thermostats to sophisticated digital controls with temperature and status read out. Heaters connected to pools and spas must have a safety high limit thermostatic control with a maximum set temperature of 42 degrees.
Controls range from the basic to the very sophisticated. Seek expert advice and consider your budget, lifestyle and most importantly, what will best match the way you want to use your pool or spa.
INDOOR OR OUTDOOR
INSTALLATION
Heaters can be installed indoors but require special fluing and may require additional ventilation specifically designed to suit the size and type of heater to be used. Never install a heater designed for outdoors inside unless the appropriate flue is fitted in accordance with the manufacturer’s instructions.
Heaters should always be installed on a stable, non-combustible base, preferably a minimum of 50mm above ground level.
Spa blowers must be located a minimum of 1.5m from outdoor gas heaters, and never in the same plant room as indoor gas heaters unless separate ventilation is provided.
COST EFFECTIVE AND
CONVENIENT
Gas pool and spa heaters are very cost efficient. Running costs are relatively inexpensive. On pools, these can be further reduced in summer by incorporating a solar heating system and all year round by using a pool blanket to stop overnight heat loss.
See SPASA Victoria Fact Sheet 14 on Covers & Blankets.
Increase the use of your pool by up to six months using the free energy of the sun
Solar systems may vary, but the basic principal remains the same. Pool water is circulated through a series of tubes (the collector) usually mounted on the roof, where heat is absorbed and the heated water is then returned to the pool. The collector can be made of either EPDM Rubber, PVC / TPR material or UV stabilised polypropylene and is usually supplied in multi-tube strips or panels.
The amount of heat absorbed and the resultant increase in pool temperature depends on the size or area of the collector and number of tubes per square metre. The location or positioning of the collector and the control system used also affects this.
SIZE OR AREA
The size of the collector is usually expressed both in square metres and as a percentage of the surface area of the pool. Australian Standard 3634 suggests a minimum collector area equal to 60% of the surface area of the pool but only in ideal, hot climate conditions. SPASA Victoria recommends a minimum area of 80% for the majority of installations. And if higher than average water temperatures, or extended swimming seasons are required, then a larger system may be necessary.
Note that the “area” referred to in relation to collector size is the area of actual collector strip NOT the roof onto which it is placed.
LOCATION & ORIENTATION
Collectors (other than those on flat roofs) should ideally be on north or west facing roofs. If not, more collector area might be needed. Avoid shade from objects ie. trees and neighbouring houses, for at least six hours every day.
PUMPING REQUIREMENTS
You can choose to use either the existing pump or provide a dedicated pump. With an existing pump remember:
• the minimum flow rate for filtration must be maintained
• the filter’s operating pressure should not be pushed above the manufacturer’s maximum
• the pump should have sufficient capacity to handle the static head and friction losses introduced by the addition of the collector circuit
The average solar system needs a flow rate of at least 100 to 200 litres per minute to operate effectively. So in most cases, a dedicated solar pump is required. Check the flow rate of the collector when selecting your pump, as this will vary with the diameter of the tubing used.
To avoid blocking up the collector with dirt and debris, use a dedicated pump with some form of strainer.
SOLAR CONTROLLERS
Nobody knows when the sun will shine so time clocks are of little use in solar heating systems. Instead, a temperature-sensing controller will operate the system only when heat can be gained.
Using a pool blanket can increase the benefits of solar pool heating. See SPASA Victoria Fact Sheet 14 on Covers & Blankets.
Heat pumps are super efficient - just 2kW of electricity can produce 6 to 10kW of heat.
Heat pumps have been used for pool heating for many years, although mainly for commercial users. The lowering cost of the technology sees it now playing a far more significant role for the home pool owner.
For the technically minded, heat pumps gather heat from the surrounding atmosphere by drawing heat through the unit. It is then transferred to the refrigerant where the temperature is increased by compressing the refrigerant.
That heat is then transferred to the pool water. In this way, heat pumps are a powered form of solar heating.
ENERGY EFFICIENCY IS THE KEY
Electric heat pumps are extremely energy efficient. They consume very little electrical energy to operate, and produce much more in the form of heat. For example, if a heat pump consumes 2kW of electricity it will produce 6 to 10kW of heat energy.
SIZING
Pool Heat Pumps range from 6kW to 300kW output. Which one suits your application will depend on careful consideration of the following factors:
- Location – local climatic conditions will have a bearing on performance
- Target temperature – it’s your choice, however as a guide:
- exercise or recreational pool 24 to 28 degrees C
- therapeutic exercise 28 to 35 degrees C
- spa pool 34 to 38 degrees C
- Pool volume – the amount of water to be heated can be determined by multiplying the surface area in square metres by the average depth (including wading areas and spa)
- Shading and exposure to wind – these can effect the heat losses and gains of heated water
- Pool position – indoor or outdoor
- Swimming season – do you want to swim all year round or just extend the season?
INSTALLATION
Heat pumps are usually installed outdoors since they extract heat energy from the surrounding air. If installed indoors, they require large volumes of intake air, and the discharge of chilled air must be vented outside away from the unit. Positioning of the heat pump should be carefully considered so that noise levels create minimal disturbance.
Plumbing can be included as part of the pump / filter network, or as a separate heating circuit. Average size domestic installations generally require a single-phase electrical connection. Larger pools may require three phase power. Where available, time-of-use or off-peak electricity tariff connection will further reduce running costs.
CONTROL
All heat pumps should have some form of flow control device to prevent the unit operating without adequate water flow. All are thermometrically controlled with either analogue dial type units to microprocessed digital devices. These types all control the pool temperature to your desired setting with the digital devices displaying the settings more clearly.
Some manufacturers also provide additional controls including time clock or pump interlock to ensure the most economical operation of the heat / pool pump. The addition of a pool blanket is strongly recommended. See SPASA Victoria Fact Sheet 14 on Covers & Blankets.