I am getting ready to do a water change. I have a 1 gallon bucket and am going to be removing 7 gallons. The dechlorinator I have says to add 1 tablespoon for every 10 gallons. I have to do it by buckets. My question is... can I add the measured dechlor to my tank water and then add the appropriate amount of water? If not about how many drops should I add to each bucket as I am putting it in? If you could respond right away i would appreciate it. Thanks in advance.