300 km... so is it quite possible that the PH is different too in the 2 locations. Did you blend the water slowly?
When I bring a fish home from the store I rest the bag in the tank and open it. Over a time span of 30-45 minutes I keep dribbling new tank water into the bag every 5 minutes. By the time I have doubled the bag's contents of water I have adjusted any PH differences to a lesser extreme.
Do you do this? Do you know if the PH is drastically different? What is your PH?