How long have you been running the old filter in your current tank? When will your new tank and filter arrive?
If your old filter has been constantly running for at least 2 weeks by the time your new tank is ready to receive the fish, then the old filter media will help a little. The longer the old filter has been running, the more good bacteria it will have, and thus more helpful it will be if you transfer the filter media into your new filter. It is hard to say at this point because we do not know for sure how long before the transferring will take place.
Do you have a water test kit? It is very helpful. If you get readings on nitrite and nitrate, it means the cycling is making progress and the old filter media will definitely be useful if you use it in your new filter. If nitrite and nitrate readings are both 0ppm by the time you are ready to transfer, then there is no value in transferring the old filter media because the good bacteria hasn't been developing enough to even convert ammonia.
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