Waterman, Herbin, diamine, pelikan, lamy, monteverde...
I'd be fine using any ink that wasn't supersaturated or shimmer or pigmented due to cleaning annoyance, but other than that, I'd only stay away from noodlers baystate inks and red inks in any pen with a sac. Everything else in my collection of over 200 inks is fine in my sac filled pens.
Red inks and baystates are fine, they'll just shorten the lifespan of the sac and require a refresh sooner. Shimmer and saturated inks are just annoying to clean.
The only times ink needs to SERIOUSLY be considered is when damage may occur that is irreparable. I don't put any hard to clean or acidic inks in my krones because restoring them will be a headache, so I want them to last as long as possible. But my eversharp flex nibs and other sac fillers get all sorts of ink.
For super safe inks, though, I don't think anyone has ever even whispered a complaint about J. Herbin's standard line damaging a pen in any way. The less saturated, the less flushing required, the less wear and tear. Herbin, 4001, and lamy are all modestly saturated, as are most birmingham colors, Namiki blue, and on the cheaper side, Hero carbon blue (a non pigmented, nice, modest blue)
Edited by Honeybadgers, 25 June 2019 - 21:18.