I wouldnt call what you plan a complete reset. Its just a rescape really.
How are you going to recycle the tank? Are you going to get an ammonia source and do a fishless cycle before returning your fish or are you only temporarily move your fish into smaller tanks while you rescape and then return them to the 19g to do a fish in cycle.
How long to cycle? No way of knowing for sure. As you are retaining the filters, if they arent allowed to dry out they shouldnt need recycling. Perhaps move them to one of the smaller tanks and keep them running while you do your rescape. You will lose some beneficial bacteria that is living on your substrate and decorations, so your cycle might need to catch up a little. If you do a good job retaining your filtration in good order it might only take a day or 2 to catch up, it might be you get an instant cycle. If you do a poor job and completely lost your cycle it normally takes 6 to 8 weeks to cycle a tank.
How are you going to recycle the tank? Are you going to get an ammonia source and do a fishless cycle before returning your fish or are you only temporarily move your fish into smaller tanks while you rescape and then return them to the 19g to do a fish in cycle.
How long to cycle? No way of knowing for sure. As you are retaining the filters, if they arent allowed to dry out they shouldnt need recycling. Perhaps move them to one of the smaller tanks and keep them running while you do your rescape. You will lose some beneficial bacteria that is living on your substrate and decorations, so your cycle might need to catch up a little. If you do a good job retaining your filtration in good order it might only take a day or 2 to catch up, it might be you get an instant cycle. If you do a poor job and completely lost your cycle it normally takes 6 to 8 weeks to cycle a tank.