Your black and gold fish looks like my Pumpkin
Well done on getting them moved over to the 30 gallon, they'll be much happier in there.
You'll still need to keep on top of water changes (maybe each day) because your filter will still be cycling - those filter additives don't work... by the time you get that bottle, whatever bacteria was in that bottle is more than likely dead. Unless you get those refrigerated ones.
I would say change 50% each day - i've not seen that stress my fish before, and that will be less stressful than living in a tank full of poison.