First and foremost, where is the gourami going if the discus are going into the 55? If it was harassing angels, it will most certainly pester your discus. I'd have the 55 gallon empty when the discus arrive.
How long was the sump running on the 75 gallon? It could have some BB growing in it already.
My suggestion is to use media from your XP4 in your new power filters on the 55 gallon. Are there any kind of sponges or floss in the XP4, or just the loose balls/rocks? I'd move some of the Seachem Matrix or the bag of Biomax into the AC's on the 55 gallon, and leave some in the XP4.
Your 75 gallon, if planted/decorated, should also have some BB in the tank itself. Just keep an eye on it -- if you see slightly cloudy water or if the fish act strange, do a large water change. I don't anticipate any issues with the cycle being interrupted, though.
As for the discus in the 55, put the temperature at 85 or 86F for the little ones and give them daily water changes of 50% if you can for the first week or two. That should take care of any cycling issues. The media from your XP4 will jump-start the cycle in your new ACs. Make sure with water that warm that you have plenty of aeration/circulation in the tank.
Definitely keep the two tanks separate. Go ahead and disconnect the sump from the 55 now. Bring the water temperature up in the 55. Don't put the media from the XP4 into the 55 gallon tank until the day you get the discus, that way your bacteria won't be starved.
How long was the sump running on the 75 gallon? It could have some BB growing in it already.
My suggestion is to use media from your XP4 in your new power filters on the 55 gallon. Are there any kind of sponges or floss in the XP4, or just the loose balls/rocks? I'd move some of the Seachem Matrix or the bag of Biomax into the AC's on the 55 gallon, and leave some in the XP4.
Your 75 gallon, if planted/decorated, should also have some BB in the tank itself. Just keep an eye on it -- if you see slightly cloudy water or if the fish act strange, do a large water change. I don't anticipate any issues with the cycle being interrupted, though.
As for the discus in the 55, put the temperature at 85 or 86F for the little ones and give them daily water changes of 50% if you can for the first week or two. That should take care of any cycling issues. The media from your XP4 will jump-start the cycle in your new ACs. Make sure with water that warm that you have plenty of aeration/circulation in the tank.
Definitely keep the two tanks separate. Go ahead and disconnect the sump from the 55 now. Bring the water temperature up in the 55. Don't put the media from the XP4 into the 55 gallon tank until the day you get the discus, that way your bacteria won't be starved.