......In an earlier issue I covered salt chlorination. I have chosen to run it again, as in the past few weeks I have come across quite a few people that have been ill-informed about the advantages of the system.
In Australia you have to ask “not to have” salt chlorination for your pool if you don’t want it. Salt chlorination, in my opinion, is the best way to have a relatively easy swimming pool to manage and enjoy.
First thing is to understand that when we talk about a salt water pool, it doesn’t mean sea water salt concentration. We use about 15-20 per cent of sea water concentration. Without tasting it you would not know it had salt in the water.
The reason for the salt is that a chlorine generator is installed in the pump room and this uses salt to create chlorine.

Three components
Yes, it is still a chlorine pool. However, the level of chlorine needed is in most cases a lot less. The salt water chlorinator system is made up of three main components ...
1 Salt in the water
2 Control unit
3 Salt cell
Salt makes the water conductive so that the electricity can pass between the plates in the cell.  If the salt level goes too low, then the chlorine production simply stops. Salt is also the raw material from which the chlorine is produced.
The control unit is a device that sends power to the salt cell. The unit controls how much chlorine is produced by regulating how long the power is applied to the cell. 
If you turn the control knob way down, then the unit might apply power to the cell only 25 per cent of the time, thereby producing less chlorine.  If you turn the control knob up, then the unit would apply power to the cell for a longer period. The amount of power applied to the cell does not increase or decrease. The control unit will often sense the level of salt in the pool and indicate the need to add more salt.
Self-cleaning units have a feature built into them that reverses the polarity of the voltage through the cell in order to clean any scale build-up off the cell plates.
The salt cell is a series of plates with opposite charges in a cell.  As the water passes between the plates, electrolysis takes place, releasing the chlorine in the salt. This is how chlorine is made on an industrial scale, but much larger.
Salt water chlorinators actually make chlorine gas which passes through the water creating the chlorine level that we read when we do a test. The beauty of this system is that it only leaves salt as a bi-product.
Another bonus is that the water balance of a salt pool is easier to maintain. Because the chlorine is set a predetermined level you don’t have the bounce you see in hand dosed pools.
The only thing that is needed is a little acid to bring the pH down as this is normally a bit high because of the salt content. Salt pools will normally run at a pH of 7.8 if acid is not used and the best pH is 7.4 to 7.6.
One thing I have noticed in Thailand is that nobody seems to take any notice of the calcium levels in the water. Water is very aggressive and will seek its own balance if we don’t artificially do it by adding chemicals.

Scale build-up
One of the first things that water looks for is calcium. If it is low the water will suck it out of the surface of the pool and surrounds. This is why you get sand wash falling apart, tiles falling off and white scale build-up around the pool edges.
In Thailand I have found that normally pools have around 50 ppm of calcium in the water, whereas salt water pools have high calcium content, around 150 to 180 ppm. Although 250 ppm is the desired level, you are close, so this means you are protecting the surface of your pool.
I cannot believe the number of pools I have seen around Thailand that are only around a year old and the surface is deteriorated so much that they need resurfacing. It is hard to get the calcium tested in Thailand as a special reagent is needed and the proper test kits that I used in Oz are hard to get.
So, by installing a salt water chlorinator system you basically solve this issue. Salt water chlorinators are easy to fit whether you have an existing pool or you are in planning stages.
Installing an electromagnetic water conditioner (EMPD) as well as a salt water chlorinator will give you the best and easiest pool to manage and the best bather experience you could imagine.
With salt water swimming pools that have the EMPD installed, you can run the chlorine at less than 1 ppm and have no issues with algae, bacteria, viruses and no more skin or eye issues.
See you next issue. Ω

Steve Johnson is the managing director of WET, Water Engineered Technologies (Thailand), which offers a range of commercial and domestic water filtration solutions, potable water, reverse osmosis, desalination systems, plus swimming pool design, construction, equipment and consultation. Contact 08484 28317 or email wtquestions@hotmail.com