Hi there
first you should only use distilled water never tap water, even distilled water from stores are not good because they tend to get flaky after a couple weeks.
the pictures show that the wrong water was used. with this smutch water it builds flacks which then block some areas of the tube and prevent required cooling especially around the anode and cathode this burns this parts and end the live of the tube.
I personally only use water from a Revers osmosis unit and still need to exchange every 4 weeks.
during this exchange I use a tube manufacturer 5% HCL solution and run this solution for about 30 to 50 minutes till the tube is crystal clear again then flush it out with pure R/O water for another 15 minutes and only then refill with pure R/O water removing all air bubbles is essential.
greetings
waltfl