Low TDS alert occurs when the TDS of the water is below 600ppm, indicating sanitisation will not be as effective. Another indicator of Low TDS will be that the OXI OUT will not retain its setting at 100%.
Most often, low TDS is caused through dilution of the pool water. Other factors can include colder water temperature, not enough flow of water through the cell housing, or a build-up of calcium on the cell plate material where they are not able to produce enough output.
You may also see this alert when starting the system the very first time on a new or renovated pool. If the TDS in the water hasn't had time to circulate throughout the pool, this message will appear however if the water balance is correct the alert will disappear once diluted.
Please refer to the attached Installation Guide which will show how to correctly balance the pool and get the TDS levels back to within range, more than likely salt is required to achieve this.
Add 5-10 kg in the shallow end of the pool and brush in when the pump is running and allow 30-60 mins for the salt to dilute.