Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
A few things that can help:
Before: As thorough vacuum of the substrate as possible. (easy with sand or gravel, not with soil) Clean filter a week before so the bacteria can recover (not much happens with cleaning the filter, but just do not do it on the same day as the re-scape)
Remove livestock to as many buckets as needed, do the re-scape.
If you had gravel substrate there is the maximum bacteria population in the top layer of the gravel. You can skim that (before you disturb anything) and store it in 3-4 mesh bags (nylon stockings work well). When the 'scape is done hang these in the tank where there is good water flow. Remove one per week.
You can add more plants, especially fast growing plants. Even if they are temporary, they will help with any ammonia spikes.
You can add more bacteria. Look for Nitrospira species.
Dose Prime or other dechlor that also controls ammonia and nitrite. Read the label for proper dosing.
Test, and be ready to do more water changes.