How to move a tank& upgrade

[a&a2]

I am going to be upgrading my 125 gal to a 300 gal. The new tank is going to sit right where the old tank is. My question is how do I move the two tanks and switch everything out?

 

[eric b 125]

i would take everything out of the 125 and into buckets. then i would move the 125 to somewhere that you could still use it as a temporary holding tank while the 300 cycles (if it is going to). i'm assuming you'll be moving the sand and rocks from the 125 to the 300?

 

[a&a2]

Yes I will be using that for my new tank. Just wondering how to not stress everything out!

 

[btldreef]

Buckets, lots and lots of buckets. And have Amquel or Prime and lots of extra freshly made water on hand. Try to put all the corals in separate buckets from the fish, but put some rock with the fish, this has worked best for me.
I'd recommend not using all of the sand, you'll be stirring up a lot and creating a potential mess. Add new sand to the new tank and seed it with some of what's in the old tank. You'll run much less of a risk of ammonia spikes this way. At least that's what's worked for me.
How much down time do you expect between closing down the one tank and getting the new one up and running?
Are you using any of the same equipment (sump, pumps, etc)?

 

[a&a2]

I need enough down time to move the old one out of the way and put the new one in. Now my filtration is undergravel filter with a canister filter so when I upgrade I will need to change all that. I am very concerned on stressing the fish out while trying to catch them. Also my substrate is crushed coral not sand