Calcium build-up and your Salt Water Chlorination System

In modern life people are very busy, they usually work long hours and struggle to find balance between work and private life. For this reason they tend to purchase different automated systems so they can devote more time to their family and friends. Due to lack of time, however, quite often the regular service of these systems is skipped and the benefits of preventative maintenance are overlooked. Some of the benefits of regular maintenance include increased efficiency, cost saving and an extended life of the system.

Despite what you may see in advertisements or what some distributors and manufacturers claim, salt water chlorine generators are not completely maintenance free systems. Your salt water chlorinator requires some regular inspections and service, same as your filtration system and other pool equipment. One of the things, which need to be inspected, is a level of calcium build-up occurring on the electrodes of your cell. Depending on your water balance and what type of salt water chlorinator you have, this build-up can range from 1-2 mm in a year to 1 cm in 2-4 weeks.

Factors affecting calcium build-up

There are two main factors, which affect the amount of calcium that builds up on your electrolytic cell. One of them is total running time of your chlorinator, another - water chemistry. Running time is simple - the longer the machine runs the greater the amount of calcium that will be deposited on the cell. The chemical balance of your pool water on the other hand is a lot more complex and often overlooked as a cause of excessive calcium build-up. It may not be enough to only check chlorine residuals and PH levels.

Another factor, which has a large effect on scaling, is Calcium Saturation Index (CSI). For more information on Calcium Saturation Index and it's effect on your pool please read the following article: Calcium Saturation Index - What it is and what does it have to do with my pool?

It is important to remember that this information applies to both standard and self-cleaning salt water chlorinators. Self-cleaning chlorine generators are usually able to reduce the amount of maintenance by a factor of 5 to 10. As a comparison, if you need to clean calcium from a standard electrode every two weeks, then a self cleaning cell will need to be cleaned approximately once every four months.

Some models of salt water chlorinators (including AutoChlor SMC series salt-water chlorinators) have built-in user selectable reversal options. This option allows user to adapt the chlorinator's self-cleaning option to suit specific water conditions. Please consult your user manual for the correct procedure of changing the reversal time.

Actions in case of excessive calcium build-up

In general if your salt cell is receiving an excessive calcium build-up the best procedure to take is:

1. Clean your cell as described below
2. Take a water sample to an experienced pool technician for a test or do the tests yourself as described in the article about Calcium Saturation Index.
3. If your water chemistry is correct (or there is nothing that can be done about it) - reduce the reversal time.

However, care must be taken when reducing the reversing time cycle, as it could significantly reduce the life span of the electrolytic cell. Normally, a reduction in the recycle times should be taken one step at a time. Reduce the setting 1 step and operate the machine for 8-10 weeks to see the result. It this is not sufficient, reduce the setting 1 step further.

Cell cleaning procedure

Procedure for cleaning your cell:

1. Turn off the chlorinator
2. Disconnect cell cable, and remove cell
3. The dirty cell should be placed in a container with hydrochloric acid. (HCI) solution: 8 parts water to one part of HCI (30-33%), as per diagram below.
4. Calcium deposits will react with the HCI - producing gas
5. When gas production has stopped, it means that the cell is completely cleaned and all the calcium has dissolved (or all the acid is neutralised and you need to repeat previous steps with fresh acid)
6. Rinse in fresh water as soon as possible - leaving the cell in HCI solution for a longer period will damage the cell!
7. When cleaning is complete, dry the connections and reinstall the cell

Please note, different cell manufacturers have different cell cleaning procedures. The procedures above are suitable for AutoChlor manufactured cells and their replicas. Please follow your manufacturer's instructions for your cell model. Do not use sharp objects to clean the cell, this may scratch the surface and void your warranty.