This is David the Justpools Service Technician
I just wanted to share with you one of my experiences with salt water chlorinators.
I had occasion to go out to a client’s residence to find out why his chlorinator was not working.
The service call had been requested by the client as his pool water tests kept showing low chlorine levels, however the client informed me that the unit appeared to be operating normally with plenty of gas coming from the cell during operation.
I arrived at the property and had a look to see what was going on.
The first thing i did was a water test to check for ph level and chlorine level, the results of the test showed that the ph level
was on the high side and the amount of free chlorine was very low.
My next step was to check the operation of the chlorinator and with the unit in operation I found that chlorinator was working normally.
After some more investigation I found the cause of the problem, it turned out that the client had the incorrect run times set up in the timer on the chlorinator. The run time set on the chlorinator time clock was from 10.am to 6pm daily.
That’s an operating cycle of 8 hrs per day.
Now the chlorinator was set on 100% output and was of a large capacity (35grams per hour) and with a run time like that for a 50,000 litre pool you would think that there would be plenty of chlorine in the pool, so how come very little or no chlorine ???.
To be able to answer this I need to explain a little bit about how the system works.
Now when you see a salt water chlorinator in operation and look at the electrode cell in the housing you will see a cloud of gas coming of the cell. This is caused by the reaction of the current between the plates of the cell and the salt (sodium chloride) in the water. I won’t go further into this as the chemical equations are quite complex, but in simple terms the sodium chloride molecule is broken down in to sodium and chlorine. The chlorine does its job of sanitizing the water and at a later stage in the reaction the chemicals recombine to form sodium chloride or salt.
The reason for that explanation is to try to make you understand that the chlorine coming off the electrode cell is of a very dilute nature and takes quite a while to build up to a concentrated level.
Now having said that you need to know that the worst enemy of chlorine is ultraviolet radiation which naturally comes from the sunlight. So in this case what was happening was that there was a dilute amount of chlorine coming off the cell and going into the pool, which was then pretty much being broken down by the action of the sunlight with the end result of a low chlorine level in the pool water at the end of the run.
The remedy to this was to do a split run, What i did was to set a morning run out of the strong sunlight hrs which was from 6 am to 9.30am and then an evening after sun run which was from 6pm to 10pm.
What happens in that setup is lets say at the start of the evening run the chlorine level is low, by the end of the evening run the chlorine level will have built up and it will sit there overnight sanitizing the water and then the early morning run kicks in and boosts the chlorine level high which gives it enough to last through to the evening run.
By using this method you can be sure of having chlorine in the water.
However this was not the only issue. the other issue was the high level of ph in the water.
When chlorine is added to water, one result is that the ph of the water is increased through the reaction of the chlorine and the water. A ph level that is above or below 7.5 has two side effects, one of them is that eye irritation can occur and the other is that chlorine becomes less effective as a sanitizer the more the ph is out from the normal range
Going back to the client, once i had added some acid to the water to bring the ph level to where it should be and added some liquid chlorine to the pool water to bring the amount of free chlorine to the right level and reset the time clock on the chlorinator,
within a few days his pool was back to normal.
I advised the client to give a daily dose of acid to the pool rather than a weekly dose to help keep the ph in balance.
Of course the better way to do this is by installing a chlorinator with a built in ph monitoring and acid dispensing system
Well that’s all for now till next time
Justpools Service Technician
Or call 1300 658 313