In previous articles I covered some basics on water treatment and how I go about clearing up the supply into your house.
Recently I have been monitoring some customer’s backwash water from point of entry “pre-house” filters and what I see is disturbing. I have stopped washing my teeth in anything but bottle water or beer.
With municipal water filtration, there is a process of dropping the dirt in the water to the bottom of a tank. This is called flocculation and the chemical used is called aluminum sulfate.
If there is no correct dosing (too little or too much), then it will stay in suspension and end up in our homes. This is not only a problem here in Thailand but in many other parts of the world.
Each day the water needs to be tested to set the correct amount of dosing so as the coagulant does its job. The process is also used in start-up of pools, especially here as the water is full of iron.
When a pool is first filled, the water would look like it is clear. Then once the chlorine is added the water is oxidised and, voila, you get brown or green water.
Then a liquid coagulant in the correct dose is used to drop the iron and dirt to the bottom of the pool, to be vacuumed to waste the next day.
Dependent on your water source, the water in your pool may be turning brown/green on a regular basis. This is due to the top-up water being used after evaporation or vacuuming – the top-up water being full of iron and some magnesium which reacts with the sanitiser that has oxidised the pool water.
This is a vicious cycle that unfortunately can only be remedied by using a different water source. It is this oxidation that is needed for the killing of the baddies in your swimming water.
I have already covered the basic of water balance and sanitation in previous issues. However, I will cover briefly some other methods – chlorine and its different types have been covered and you know I recommend salt chlorination as the safest and easiest way to have a low maintenance pool. Bromine, algaecides, oxidisers and ionisers are other methods of sanitisation.
Bromine is really only recommended for indoor pools spas as it is affected by sunlight very quickly. When bromine is in use, you would need to shock your pool on a regular basis with an oxidiser. Not enough space here to explain why!
Algaecides are used to control algae and are really only an aid in keeping your pool clean. Better suited to fish and plant ponds as chlorine is not able to be used in these areas. The picture below shows a pool with an algae problem. If you look after your pool correctly then algaecide is not needed. If over-dosed in your pool, your hair can turn green.
Oxidisers work with sanitisers to rid your pool and spa water of pollutants. By definition, sanitisers kill things like algae and bacteria but they work very slowly and inefficiently when trying to remove waste products such as sweat, skin oil, shampoos, soap and urine.
This is where you need separate oxidisers. Oxidisers destroy these undesirables. They do their part by breaking down the contaminant’s structure, rendering them vulnerable. The sanitisers can then attack and kill the organisms. Some products, such as chlorine, act as both a sanitiser and an oxidiser. Bromine, on the other hand, does not oxidise very well and therefore needs the aid of a separate oxidising chemical to properly clean your pool and spa water.
The marriage of sanitisers and oxidisers is an almost foolproof method of keeping invaders out of your pool and spa water. Ionisation is a process where an electrical current is sent to sacrificial anodes placed in the pipe work inside the pump room.
These anodes introduce metals such as copper and silver into the water to help kill undesirables.
Ionisers are only an assistant and should be used in conjunction with a residual sanitiser. They are frowned upon by the Health Deptartment in Australia because the seller’s claims of “no chemicals needed” and they are being banned in shipping by the European Union.
As stated in previous articles, all this is made easy by using salt chlorination and an electromagnetic pulsing aystem I market.
See you next issue.
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