I have noticed that water changes are better when they are done slowly. I still drip water in slowly even at 30 days, partly because I am afraid to make many changes. The bacterial infections do seem to wipe them out fast when they occur. I think you may be correct about the mouth problems. From what I can tell they don't seem to have them now so they may be able to get past them. Best of luck Kungen, let us know how it goes.