My plan was keeping it in a reservoir and having 64 of it in each jar. What's the limit on how much essentia can be kept in a reservoir?While you CAN use the reservoir, I personally prefer the crystal method since it's easier to store and get specific amounts of essentia from, plus you don't have to do jar management or have a void jar wasting a bunch of it. However, I'd assume you can pipe the stuff into and out of a reservoir just fine, but I haven't played around with it so I'm not sure if there'd be any issue with pipes and where they can be placed on it. On the plus side, having it all in jars means you can use essentia mirrors to fuel your Infusion Altar.
But they're WIZARD towers, of all the things that might survive those are the ones I'd most expect to.