For the ones who say they wouldn't I am curious to know as to why they think it is more dangerous than Krylon Fusion spray paint....
But I will use the tried and true Krylon instead of Sharpie. Getting a 2nd set of filter pipes so I can keep my tank online and just swap in the new ones. Sucks because it's $13 per spray bar so I was hoping to pull them out, coat with Sharpie, and put back in, instead of needing to buy new and paint and dry.