Pool Sanitation Systems

Erosion feeders

Erosion feeders in their simplest form are a floating canister, which is usually a cone shaped plastic container, with large numbers of holes in the body. They will normally have a screw on, or clip on lid to allow chlorine or bromine tablets to be place into the body of the container.

When the container (feeder) is placed onto the pool or spa, water enters through all the holes, slowly eroding the tablets, and depositing chlorine or bromine into the water.

The type and number of tablets that are used will also determine how often they will need to be refilled. There is little or no control over the rate at which the tablets dissolve.

There are however, more sophisticated erosion feeders. These products usually consist of a moulded canister designed to hold either chlorine tablets or bromine sticks, and are mounted in the return to pool line. They are usually fitted with barrel unions at aid installation.

Most commonly they will be fitted with some type of adjustment, to regulate water flow through the canister. This controls the rate of erosion of the tablets or sticks, and thereby the amount of chlorine/bromine in the pool. Some erosion feeders are fitted with electrically operated solenoids and can be controlled electronically.

Electronic controlled feeders

Electronically controlled feeders utilise either small peristaltic or diaphragm pumps, or suction solenoids to feed liquid chlorine or hydrochloric acid from a storage drum, into the pool.

The most basic of these feeders can be adjusted to add small amounts of the desired chemical to the pool at regular intervals. They may also be coupled with time clocks to operate only at specific times.

More sophisticated versions may include probes to sense and control chlorine levels in the pool and automatically adjust the amount of chlorine being added to the water.

Some units also incorporate a probe to test and control the pH of the water. These units incorporate a second pump to automatically add acid.

Top of the range models may include many extra items, such as digital readouts, warning lights and/or buzzers to indicate low chlorine levels, transformers for lights, time clocks, and some even provide printed data sheets to record the units operation.

No matter which unit you choose, remember that liquid chlorine loses its effectiveness the longer it is stored. Make sure the storage drum has a properly fitting lid, and the size of the drum allows for reasonably short turnover times, say 30 to 60 days.

It should be pointed out that any of these feeder pumps should only operate when the filtration pump is running.

If the chemical doser is to be used in conjunction with a gas heater, it is important that the injection point be located downstream of the heater in accordance with AS 5601.

Always follow the manufacturer's instruction when installing your automatic chemical feeder, or have it installed by a SPASA accredited technician.

Remember that while these systems are automated, maintenance and checking of water quality parameters is still required.

Salt chlorinators, or chlorine generators, use the process of electrolysis to create sodium hypochlorite, or liquid chlorine. Saltwater passes through an electrolytic cell which converts salt in the water into chlorine gas which, when dissolved in water, becomes liquid chlorine. They consist of two main parts, the cell and the power pack.

The cell

The cell is where the chlorine is generated. It usually consists of a clear plastic housing containing electrodes. Anodes and cathodes are made from, or coated with, exotic metals like platinum, titanium and aridium. The cell and electrodes may differ in size and configuration depending on the brand of chlorinator, however the principles of their operation remain the same. Caustic Soda is also generated in the cell, so a salt chlorinated pool will use more acid than other types of chlorination.

Some models that use a single polarity cell will need cleaning with 'Cell Cleaner' monthly. Cells that have reverse polarity are capable of self-cleaning and only need to be manually cleaned when white calcium deposits form in the cell.  

The average life of a cell is 2 to 3 years and chlorine output from the cell decreases with time. The first sign of deterioration is Black Spot Algae forming in the pool.

Power pack

A power pack is a box connected to the mains power which lowers the voltage to the cell for it to work. It also has a dial to raise or lower the chlorine output of the cell and a timeclock to operate the pump. 

The power pack will not operate if no water is flowing through the cell and will shut down if too much salt is in the water or if salt is added with the pool cleaner, still attached (which will suck up neat salt). The salt cell will also be damaged if the salt content is too low. Salt can only be lost through backwashing, water being splashed out or the pool overflowing. Consult the manufacturers’ instructions for ideal salt levels and correct operation.

Selecting a suitable salt chlorinator

A number of factors will affect the selection of a salt chlorinator.

1. the size of the pool or spa - larger pools need larger chlorinators

2. bather load - heavy loads consume more chlorine

3. size of the filtration system - poor water flow will require longer running time

4. summer water temperature – high temperatures and strong sunlight cause faster loss of available chlorine

How much salt to use

The amount of salt needed for the salt chlorinator to produce sufficient chlorine varies depending on the type of chlorinator. Most models require only weak salt solutions of from 0.3% to 0.6% (3,000 ppm to 6,000 ppm) to effectively chlorinate a pool. These levels are about one seventh the level of salt in sea water.

The manufacturer's recommendations should be strictly followed to avoid damage to the chlorinator and to ensure adequate chlorine production.

Replacement salt is only required to replace normal consumption and loss from filter backwashing, splash-outs and any overflow due to rainfall.

Other chemical requirements

The requirements for chemical balance are the same for electrolytic chlorination as they are for traditionally chlorinated pools. pH, Total Alkalinity, Calcium Hardness and chlorine levels should be checked regularly. Chlorine stabiliser (isocyanuric acid) should be added to the pool and maintained at approx. 30- 50ppm, to reduce chlorine loss due to UV rays.

During periods of high bather load it may be necessary to manually supplement with liquid chlorine to maintain correct chlorine levels, and regular superchlorination or shock dosing should be carried out.

An important consideration

When using salt chlorinators with gas or electric heaters and heat pumps, care should be taken to ensure the production of chlorine is adjusted to suit the pool or spa as the heaters internal components can be damaged by excessive salt and/or chlorine levels. This is particularly important when operating for extended periods during heat-up.

Safely and effortlessly purify your pool water without the need for adding chlorine, high salt of expensive minerals. These systems are:

Gentle on eyes and skin – one in three people suffer from a skin condition such as psoriasis, eczema or dermatitis. These systems provide a comfortable alternative.

Cost effective – save time and money with less chemicals, reduction in power consumption and the ability to recycle pool water without dilution.

All natural – using nature’s minerals such as copper and silver ions rather than chlorine, it feels incredible to swim in a pure freshwater pool that is not only healthier for you, it’s healthier for the environment, your pool surrounds and equipment.

An ioniser consists of two parts; the electrode assembly consisting of two (or multiples of two) bars of metal usually made of an alloy of copper and silver and the electronic control unit.

The electrodes are usually installed in the pool’s recirculation system. The control unit supplies the necessary extra low voltage across the electrodes. The resultant current produces positively charged ions of the constituent metals which are carried into the pool and become part of the chemistry of the pool water.

Silver ions act as a disinfectant and copper ions act as an algaecide. Although these ions kill algae and bacteria and provide a measurable residual, they do require an oxidiser to be present for the oxidation of organic wastes. Most manufacturers recommend the use of chlorine, but non-chlorine systems are also available.

Follow the manufacturer’s instructions to prevent the possibility of discolouration of the pool surface. Maintain the pH and the copper residual within the manufacturer’s recommended levels. Consult with the manufacturer to check if the equipment is suitable for the desired application.

The ionisation of copper/silver alloy is a means of purifying pool/spa water, not chemically balancing it. Therefore normal procedures should be adopted to correctly balance the water.

Ozone is a sky-blue gas and is formed naturally by the action of the suns UV (ultraviolet) rays splitting and oxygen molecule (O2) and one individual oxygen atom attaching itself to another oxygen molecule. This is ozone and is expressed as O3. It can also be formed when a large electrical discharge passes through oxygen (eg lightning). It is a relatively unstable, highly toxic gas which decomposes to re-form oxygen and is a very effective bactericide.

Ozone generators produce the gas by one of two methods:

Ultraviolet light (UV) – generation of ozone using UV is achieved by passing air over a UV light source and then mixing the gas with water.

Corona discharge – in this method, air is passed through an electrically charged chamber. What could be called a miniature lightning storm is created in the chamber which electrically converts the oxygen into ozone.

Note: The concentration of gas produced in both types of systems can vary and care should be taken when selecting a unit to be sure that ozone output is appropriate for your pool or spa.

Ozone treatment has been used for many years, particularly in Europe, for the treatment of municipal water supplies and also large commercial and Olympic pools. Recent ozone technology developments have enabled manufacturers to produce smaller more economical generators, much more suitable for domestic pools and spas.

Ozone is one of the most effective disinfectants and oxidisers available and once introduced into the water it starts to work immediately, killing bacteria and oxidising organic waste. As ozone is not highly soluble in water, the ozone must be injected into the water by either a compressor or venturi system.

However, as ozone is also toxic, all traces must be used or removed prior to reaching the pool. As there can be no residual of ozone, some other form of residual sanitiser like chlorine or bromine must also be used in order to provide continuous protection when the ozone generator is turned off.

Naturally, using ozone as the primary oxidiser, means a much smaller amount of chemicals will be needed to sanitise the pool and provide the necessary residual.

When using an ozonator in pools and spas treated with chlorine, always follow the manufacturer’s recommendation on maintaining pH.

In pools treated with ozone and bromine, the oxidising power of ozone will regenerate the inactive bromine, reducing the consumption of bromine product.

Ozone remains in the water for only a short time and therefore has no effect on pH or water balance, nor does it contribute to Total Dissolved Solids.

The use of a correctly sized and operated ozone generator with a pool disinfecting chemical (eg chlorine), will keep a pool clean and reduce the need for shock dosing.

These systems are typically a hybrid solution that combines two traditional methods of sanitising water. Ionisation and Oxidisation are combined together to deliver crystal clear water that is very soft to swim in and has no smell, feel or taste of chlorine or high salt and minerals.

Pros:

1. Programmed to size of your pool making it simple to use

2. Ideal for asthmatics, psoriasis and eczema sufferers

3. Up to 50% less chemical and 80-90% less salt/minerals

4. Longer lasting pool equipment and pool surrounds

5. Water saving – re-use water for garden or grey water

6. More environmentally friendly

Cons:

1. Very high copper levels can cause staining

2. Electrodes will need replacing (average 3-4 years)

3. Phosphate levels should be checked every 8-12 weeks