Chlorine

[sometime]

Just a quick question.

When a salt chlorinator makes chlorine and then the spent chlorine reverts back to salt, the only chlorine in the pool should be free chlorine?

So is the need to test for total & free chlorine is inappropriate?. True or false

[Chaichara]

True.

The use of a saltwater chlorinator is based on the totally automatic function according to your settings after a trial period of several days to finally adjust the chrlorine production percentage.

Under normal conditions you would hardly ever need to check the water unless you suspect a misfunction of the chlorinator, or if you have ignored the 'Add More Salt' warning. (This can happen if the water has been heavily dilute by massive rainfall°, or over enthusiastic use of backwashing.

All you need to do is occasionally use a simple Chlorine and pH tester and check that the colours match the recommended default levels. When using a saltwater chlorinator, it is critical that the pH is kep as close as possible to 7.2

Most owners don't really need to know the chemical science (even I don't). It's a bit like driving a car really, all you need to do is occasionally check the dipstick and top up the oil if required, without needing to know why. You don't do it every day, and theoretically, a warning light and signal will go off before there is any danger of the engine seizing. In a well maintained car, the regular service intervals every few months will probably arrive more often than you need to check the oil. The same goes for swimming pools.

However, if you are intereted in the academics, this site will give you all you need to know about pool chemistry:

http://www.deh.enr.state.nc.us/ehs/chem.htm

For others, just Google "pool chemistry".

[gilbreth]

To reply, it is important to define "free chlorine" (that chlorine that has yet to oxidize anything), combined chlorine (that chlorine that has attached itself to something and is oxidizing) and total chlorine (the sum of FC + CC). The chlorine that exits the salt system is indeed free chlorine, until that time that it encounters something that it can breakdown and oxidize. Theoretically, this could happen in the piping system back to the pool. Even in a salt pool though, somebody could pee and the existing FC would oxidize that urine into a "chloramine" which is a foul ammonia based chemical that reeks of chlorine. In this case, it would be good to test for all three - FC, CC, and TC. If there are no suspected issues though, not needed. Salt systems are the greatest.

Gil