Gravel Change Will Tank Mini Cycle

[smoggs]

I'm about to relocate my tank any whilst its empty i'm going to change the current play sand / gravel mix that realy looks a mess, will changing set tank to cycle again again or can i readd fish once waters settled.
Also is 3mm dorset gravel ok for use with guppy?

 

[CKutz]

no it won't.
keep your filter media in a bucket of old tank water while you change the sand to gravel. it should be ok.

guppies dont' care what kind of substrate you have.