There are a few reasons that may make it seem as though the Mini may not be working. First, it is important to review the types of chlorine, free chlorine, combined chlorine, and total chlorine.
Free chlorine is chlorine that is available to combine with contaminants in the water to disinfect and sanitize the water. Free chlorine is residual chlorine.
Combined chlorine occurs after it has bonded with contaminants. In this state, it is no longer able to continue sanitizing. It has done its job and must wait for additional chlorine to come in to continue disinfecting the water.
Total chlorine is the total amount of chlorine in the spa, the sum of both the free chlorine and the combined chlorine that holds the dirt, oils and other compounds that make the water dirty. Free chlorine should be higher than the combined chlorine. If combined chlorine is higher than your spa water will have a strong chlorine odor.
Why is my Mini not producing?
1) Did you shock your fresh new water?
When first installing the Mini, it is crucial to begin with fresh new water, and then add shock to provide a residual of free chlorine. The Mini's job is to maintain the free chlorine residual. It can takes days to get the spa from 0 chlorine to 2ppm in your spa if you do not start with a residual of free chlorine. You want your free chlorine between 2-4 ppm.
2) How many hours is your system running a day?
Depending on usage and size of your spa, you might need to increase the run time to keep up the higher demand for chlorine. Adjust your Mini's hours of operation, so it meets the chlorine demand.
3) What is your salt level?
The optimal salt level is between 2000 to 3000ppm of salt. If your salt level is too low, it will not be producing enough chlorine to keep up the demand. Add salt accordingly to get back within the salt range. To know the amount of salt needed for your spa go to https://poolchemicalcalculator.com/.
4) Does the cell need to be cleaned?
Check the cell for calcium build up. If the cell needs cleaning, soak the cell in one part muriatic acid four parts water until foaming stops, it takes about 5 to 10 mins. Depending on how much build-up has accumulated, you might need to soak it again. Just make sure not to soak at one time longer than 10 mins, but do it in increments.
5) Test the water chemistry
Testing the water is a very crucial step in keeping up with chlorine. If the water chemistry is off, then it can affect the chlorine. For example, if your pH swings too high or low or the stabilizer is too high above 80ppm, it causes the chlorine to become unstable. The optimal chemistry levels are below. Another level to check at your local pool store is your phosphate and nitrate levels. They should be 0ppm. If they begin to increase, they cause a higher demand for chlorine. Also, phosphates are algae food and allow algae to grow in your pool water. To remove phosphates, you will need to use a phosphate remover. To decrease nitrates, will need to drain and the pool and add fresh. It is best to ask your local pool professional on how much. Total Dissolved Solids, TDS, could be another culprit in chlorine demand. TDS is the measurement of the total amount of dissolved material in the water. The TDS levels in your spa water should less than 1500ppm after subtracting your salt level. TDS, like nitrates, you will have to dilute the pool water with fresh water.
The optimal ranges for your pool chemistry:
Free chlorine 2 -4 ppm
Salt Level 2000 - 3000ppm
pH 7.2 – 7.6ppm
Total Alkalinity 80 – 120ppm
Cyanuric Acid 60 – 80ppm (if not using a spa cover)
Total Dissolved Solids 0 - 1500ppm (after subtracting the salt level)
Calcium Hardness 150 - 250ppm
6) How old is your cell?
The cell blades will come to an end and will not be able to produce chlorine. A salt cell life is about 5,000 hours run time, and the blades wear down over time. If the cell is coming close to the end of its life and there is a demand for chlorine, the system could have a harder time keeping up with the demand. Once the blades are used up, it is time to replace the cell.
7) Does the cell show bubbling while in the water?
First, ensure the Mini is making chlorine by placing it in the salt water and looking to see lots of tiny white bubbles coming off the cell. If so, the Mini is producing chlorine correctly. To check the production of the cell, place the cell in a smaller container of salty spa water. Once in the smaller container, let in run for a few minutes and then check the water. Is there chlorine present in the water? If so then it is producing, and something in the water chemistry is causing a demand for chlorine.