whoa. this sounds too complicated.
right, so you take said fish. put them in a half filled bucket with water from their current tank. then you take some water from the other evil tank that they dislike. add some in.
then you do some chores and what have you. come back, and add some more water in (maybe even fill the bucket with evil water). the whole process can take a few hours if you like.
then plonk the fish in the new tank they did not like. they should be fine - if they are not - consider the possibility that an unseen contaminant is in the water (like aerosol spray).
do not worry about your pH. I am almost certain something else is to blame.