marker for tank exterior

[Don E]

Hi- I'm looking for a bright marker to write on the outside of a tank. I've been using Expo brightsticks which look great for about eight minutes but as they're water soluble, the writing tends to smear fairly quickly. Someone recommended an alcohol-soluble product called Liquichalk, but I can't find it in Canada.

Does anybody know what the LFS's use?

Thanks for your help.

don