Question: How to change substrates in an established tank

Roughly 3 months ago I acquired an axolotl rescue. When she arrived she was on black sand that is (in my opinion, no offense!) unattractive, as well as not quite as smooth/fine as I would like. Now that shes doing well, and thriving, (and I know more about her!) I'd like to change the substrate to play sand. How should I go changing the substrate in an established tank? I understand keeping her hides/plants in tank water as to not disturb too much bacteria etc, but any technique suggestions? She has a canister filter with the flow reduced and a spray bar, will this completely crash the tank? I just look at the aquarium and think to myself... this is going to be a project! I want to be fully prepared before I get started.

Thank you guys so much for the help. When I took her in I had absolutely no idea how to care for her (nor did her previous owners!), but couldn't stand to see see her live in the condition she was, and its really thanks to you guys that shes doing so well.

The filter bacteria mostly live in your filter, so as long as they are maintained it shouldn't be a problem. Yes, some bacteria lives in the sand, but if you monitor your water quality once th sand is changed you should be fine.

Make sure you have extra time set aside before you start the process, I changed the substrate in my fish tank out to sand and it took forever and was really messy (although sand might not have as much debris in it and Axies aren't as messy as a bunch of fish) so an extra set of hands would also be incredibly useful, as well as two buckets. Good luck!