I was fortunate to be home today and noted that I kept on hearing my Tunze 3 nano ATO activate. I thought this was weird and went to check on the tank and saw that the sensor was completely submerged and the water in the tank very cloudy (I dose 2 tsp kalkwasser/gal in my ATO reservoir). I immediately unplugged the ATO and removed the cap of the sensor to reveal significant fouling of the device. I had just measured all my parameters this AM prior (or at the beginning) of when all of this was happening. Ca was 380 Mg Alk 9.4, Mg 1250 pH 7.7. After appreciating the ATO failure I checked the pH again and it increased to 8.1. All life in the tank other than my chronically dying torch seem to be doing okay. I am currently soaking my ATO sensor in citric acid and will be performing a water change shortly. Just not sure how much of a water change that should be and if there is anything else I should be doing. Your advice would be appreciated.


Last edited: