Rebuild

[Rudles]

Hello. I kinda let things go and will soon be rebuilding my 20 gallon high. It's presently a dirted tank and I plan to use this method again. I plan to move my angelfish and my corydora to a 10 gallon for the rebuild. My plan is to use my existing water, split between the rebuild and the 10 gallon since it has established bacteria. I plan on getting the rebuild done in 6-8 hours. How long should I wait before moving my fish back into the 20 gallon tank?

[Jungle Fan]

The water is not the deciding factor, your filter media, i.e. sponge, or bio media with beneficial established bacteria colonies is what you want to keep alive during your rebuild. I remember when I first started in the hobby in the 1960s, there was still a lot of talk about 'aged water' but really what will keep your tank from having to go through full blown cycling again is to keep the filter media in use. Nothing wrong with using your current water but just make sure whatever type of filtration you might use to keep the media wet and in flow. If you manage to do this there would be nothing wrong with moving your fish back immediately as long as you use the same filter with the same media, however you might want to let any dust settle first.

[Rudles]

Thank you. I was definitely not planning to clean the media in my canister. It sounds like it would be a good idea to get the canister up and running in the 10 gallon for the duration of the build. 

[Anita]

The beneficial bacteria also colonize on plants, wood, decorations, and substrate. So perhaps transfer some of your established substrate, including the top layer (if you have "capped" dirt). 😎