According to neptune rep. We were trouble shooting my trident. Calcium goes thru the filters in an rodi system. I was told to get steam distilled water.Correct me if I’m wrong but isn’t that the same water coming out of our rodi systems, from my understanding we use the pre filters to clean-up tap water to make it more pure about 90%(so the resin doesn’t deplete fast) and the di resin does the rest. Without the pre filters we would be going through that resin in a few days if not hours. I’ve had to make a couple hundred gallons of deionized water for work and it was just a huge cylinder with di resin.