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Salt Water Chlorinators - frequently asked questions & answers

Chlorinators go in-line after your pool water has been filtered and just before it returns to your swimming pool. The control unit feeds a small electrical charge to the electrodes so that electrolysis occurs inside the housing.

As the water passes over the electrodes, the salt in the water (sodium chloride) is broken down into hypochlorous acid and sodium hypochlorite – sanitising agents that destroy bacteria and prevent algal growth. Salt water chlorination is a closed system. Both hypochlorous acid and sodium hypochlorite are unstable, especially in sunlight, and eventually revert back to sodium chloride so that it can be re-used over and over without the need for additional salt. The only time salt is lost from the pool is during backwashing or whenever water is discarded, so salt should not need to be added frequently.

As a general rule, older electrodes use a mesh material, while newer electrodes usually have solid plates as shown in the images on the CHLORINATOR PARTS page. There is no detectable difference in chlorine output between the two types. However, mesh becomes brittle and easily damaged after around 5 years of use and Aquamech will not attempt to repair mesh electrodes that are obviously older than 5 years.

Granular and liquid chlorine both contain chloramines, also called ‘combined chlorine’, which are the chemicals that cause sore eyes, turn hair green and have a strong chemical/chlorine smell. When chlorine is produced by a salt water chlorinator the chloramines are burnt off during electrolysis in the housing before the water is returned to the swimming pool, so they do not affect pools with chlorinators.

The white build up on the electrodes in your chlorinator is mineral calcium. Just like in your kettle or iron, it comes out of the water when water is heated and starts to build up. You can reduce the speed that it builds up by making sure your water chemistry is correct – see the WATER CHEMISTRY page.

The white build up on the electrodes in your chlorinator is mineral calcium. Just like in your kettle or iron, it comes out of the water when water is heated and starts to build up. You can reduce the speed that it builds up by making sure your water chemistry is correct – see the WATER CHEMISTRY page.

It is very easy to clean your electrodes:

  • Switch off your chlorinator and unscrew the electrode from the housing. Disconnect the leads if you are able
    Cut the top off a 2L plastic soft drink bottle and fill it almost to the top with tap water
  • Using gloves add pool acid (hydrochloric acid) to the water in the bottle so the dilution in the bottle is about 9 parts water to 1 part acid – ALWAYS add acid to water and NEVER water to acid. If the mix is too strong it will eat the coating off the electrode and ‘kill’ your cell so err on the side of caution
  • Submerge the electrode plates in the water/acid solution, taking care not to submerge the plastic cap or the pins
  • Within a few minutes you should begin to see the calcium falling off the plates in large pieces. Leave it in the solution until the plates are clean
  • Screw the electrode back into the housing and the unit is ready to run.

Reverse polarity chlorinators are also known as self cleaning because they are designed to minimise the amount, and reduce the speed, of calcium build up on the electrodes. Regular electrodes have alternate positive (+) and negative (-) plates, and calcium builds up on the negative plate during electrolysis. In a reverse polarity chlorinator, both electrodes are identical and the controller unit reverses the polarity of the electrodes (the + plate becomes – and vice versa) about every 8 hours of operating time, so that any calcium that has built up re-dissolves.

If you have a digital chlorine output readout on your controller you may see that sometimes it reads as a negative number, this is not an error, it means that it is operating on reversed polarity and is still producing chlorine.

The controller unit is like any electrical device and may last anywhere between 5 and 30 years. There is no ‘standard’ lifespan, although protecting it from weather and vermin will result in a longer life. The leads are exposed and heat up and cool down with use, so they often wear out within 5 years or less.
The electrode/cell is probably the most sensitive component and lifespan will depend on how clean (of calcium) it is kept, how often the chlorinator is used, and at what output, and the quality of the original construction materials. As a general rule you should expect a cell to last around 5 years and mesh cells usually can’t be serviced after that period.

One of the biggest causes of damage to the controller unit of a chlorinator is vermin, ants and geckos in particular. To prevent this from happening you can try any or all of the following:

  • Use sticky ‘fly trap’ type paper around the controller to stop vermin before it enters, this will need to be replaced periodically
  • Seal any entry points with fly screen or mesh
  • Smear grease on the mounts between the unit and the fence or wall
  • Smear grease around entry points.

Firstly you need to know the size of your pool, that is, how many litres it holds.
Calculate your pool size here: POOL SIZE CALCULATOR
Go to the CHLORINATORS – PRODUCTS section of this site; each product includes information on how many grams/hr of chlorine they produce and what size pool they are suited to.

Install a chlorinator and add salt! There really is nothing else to it.

Depending on their chlorine output electrodes have different sized plates and different numbers of plates, the coating on the plates is extremely expensive (a 100g vial costs about $2,000) so more plates in the cell and larger dimensions (surface area) results in higher production costs.

As with car parts, both original and aftermarket versions of the more common cells are available, aftermarket cells are always cheaper than originals. Some manufacturers use a computer chip inside the cell cap, or some other method, to prevent their products from being reproduced. Obviously if a manufacturer can monopolise the market for replacements they are going to be expensive.

If cell replacement cost is a consideration when buying a chlorinator, look for popular brands that don’t use overly large or specially customised cells, and ask Aquamech for advice.

All items/products remain the property of Aquamech Services Pty Ltd until payment in full is received.

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