Sorry, I wasn't clear with my last response....Prime is fine to use and it is one of the better dechlorinators when you have chlorine and chloramines in your source water-as well as ammonia in the source water to start with. The ammonia neutralizer products change the ammonia to ammonium and both live plants and beneficial bacteria can use the ammonium just like ammonia for a food source.
What I meant by you not needing to use the old water from your old tank in the new tank-Is that it contains nothing that is needed in a new setup. The beneficial bacteria for the nitrogen cycle are sticky and adhere to all the surface areas within the tank, in the top layer of the substrate and on the filter media-very little are in the water column itself.
The old tank water is dechlorinated-but it may be full of byproducts you don't need or want in the new system and its best IMO to start with fresh dechlorinated water.
If your source water contains chlorine/chloramines-you have to use a dechlorinater with any new water added to the tank. Partial water changes, full water changes and top offs....