Other healing items use the formula on this page. They award HALF the amount you heal in XP.
If Bacta Tanks followed that same formula, your XP gained would be dependent on the total HP of the entity you throw in the tank. Syn would go put herself in a bacta tank in her off hours to get over 500XP for an 8-hour period.
Also, Bacta Tanks don't require medical skill (either indirectly or directly) - they're Plug 'N Play. *shrug* Not reasonable just with respect to other healing items.
Comparing to a similar-timer'd action that awards XP though: Upgrading a Door to lvl 3 is what... 60XP for 12 hours? Doors upgrading is limited by the accessibility to lvl 2 doors, and Bacta tanks are only limited by supply of patients and refills.
One other thing to note, Bacta Tanks do not root you in place, so you can theoretically have a stack of ketifrees and injured NPCs and hop from room to room, vehicle to vehicle loading NPCs into Bacta Tanks, so at the end of a set of slightly-offset 10hr (thought it was 8, oh well) timers, you have 30XP x Ketrifees x 4 rooms per Ketrifee. This much more like recycling than Doors or Medical Item usage. Small XP is best.
Assuming no practical limit other than Time setting it up... 120xp per Ketrifee, say it takes you a convervative 5 minutes per room to set it up (20 mins per Keetrifee), you could spend 1 hour of your day setting up patients in the bacta tanks, and wake up the next morning with another 360XP while you go off and do other things. If you spent 5 hours spread out over the course of your day, you're looking at closer to 1800XP a day, which is 45 perfect combat rounds' worth of XP... which is 22.5 hours worth of cooldown time. 8 hours' worth of back-to-back perfect combat rounds is 640XP.
...Somebody should go check that Bacta Tanks don't let you heal unharmed NPCs.
Never thought about it from a farming point of view, could definitely be abused. Just confused me why I was getting almost the same XP for healing myself to full and using 3 refills compared to one use of a medikit.
There should probably be a much lower amount of XP rewarded for healing another entity with a tank, or no XP at all.
We have a new action slot system coming in the pipeline that will likely limit the number of medical actions you an initiate to remove that potential for abuse (but you do have to buy all those tanks, refills, vehicles, and get the damaged NPCs so it's quite an investment in the first place).