At some point, the chemical crystallizer lost the clear button. I don't think this was intended, so here's a bug report, lol. And yeah, I'm stuck... only way to resolve the issue is to build a new one, as it retains the fluid/gas when breaking

Thanks for your comment and help, Dawnflash! Not sure if I'm brave enough to actually try the workaround, lol - I'm op on the server so I'll probably just give me a new crystallizer. :) Hopefully the issue will be fixed on future versions. Really annoying for people without op and/or technical skills.

I actually have that button in the latest Mek version...
EDIT: Not really, that was my Soartex res pack.
Anyway, a hotfix by the user can be done by editing your player NBT file, like this:
http://prntscr.com/7ob2jv

Just go ahead, delete that tag key and you're all set. Of course, you need a NBT editor and access to your player file. If you put the Crystallizer in the first slot of your hotbar, you will have the crystallizer as the first item in the Editor. Good luck :)

Shift-click the gauge with a gauge dropper, it will clear all its contents :)