When I freshwater dip, I match temp and pH. Get a pH test kit and two vials if possible. Put your tank water in one with the pH drops and your RO water in the other. Your RO water should be around 7 and your tank water around 8. Depending on the water volume, put about a table spoon of baking soda in your dipo water and stir it in. Test the pH again and see where it is. Keep doing so until the vials are the same color.
Then test the temp of your tank water and match the dip water accordingly. Assuming the dip water is cooler, heat some ro water in the microwave and put it in a zip loc bag and float it, stirring the dip water until the temp is within 1 degree of your tank. 1 degree warmer is better than cooler.
Then transfer him to your qt. Hopefully you have medication on hand to get the treatment underway. The dip only provides temporary relief.