Can I cycle a tank this way?

[CleverBs]

I need to replace the rock in my 75g so I am wondering can I cycle my rock in a 40g and move it to the 75g without having a cycle n the 75g? I have fish that must stay in a tank. I'm thinking of leaving about 30lbs of rock in the tank and killing then recycling the other 60 lbs of rock then remove the 30 lbs and replace it with the 60lbs then do the same thing with the last 30 lbs and move it into the tank. Will t his work? My worry is the rocks won't be sitting in the 40g the way they will be afar rock scaping the 75g so I fear this not working.

 

[Supra]

I would think it would be fine. I have a 100lbs in a brute container with a mag 9.5, I ad ammonia every day to keep alive. Maybe a mini cycle?

 

[CleverBs]

I would think it would be fine. I have a 100lbs in a brute container with a mag 9.5, I ad ammonia every day to keep alive. Maybe a mini cycle?

my probaklem is fish will be in the tank so I cant have a cycle enough to hurt them. I would die if any of the fish that are currently in there died.

 

[Supra]

I'm in the same boat, going from 40, to 125 and I don't want to be doing large water changes if there's a problem, I'm adding fish also because I need stuff from that setup for the new one