You are experiencing salt depositing on the cone tip due to the drinking water matrix. What type of cones are you using - I assume the standard Nickel sampler (with copper base) and Nickel skimmer?
Also how are you cleaning the cones? We would recommend simply sonicate in Ultrapure Water for around 20 minutes with each cone in its own plastic beaker.
You can find a video to guide you through the process "Part 4: Interface Region" here:
Depending upon your sample throughput it may be normal that you need to clean the cones every week to remove excess salt deposits from around the tip. You may be able to achieve longer time between maintaining by using uHMI mode and by using argon humidifier (part no. G8400-60700).
Another note: If sampler cone lifetime is an issue due to corrosion of the copper base I would recommend you switch to the Ni-plated sampler cone (part no. G3280-67061)
Hope this helps!