Setting up a tank for my son and I want to make things as easy and mess free as possible. The tank is right next to his sink so I was looking at something like the Aqueon water changers that connect to the faucet so he can go directly to the sink and not worry about buckets, etc. If we fill directly to the tank and then add Prime dechlorinator is this okay? or should we add the dechlorinator to the water first, mix and then add to the tank? Also, I assume we need to get the temp of the water close before adding it back? How close to the tank water?