im switching from my 75 gallon to my 125 thats been sitting in my garage empty.
my plan is to transfer all the rocks, substrate from the 75 to the 125 and all decoration and move the 75 gallons of water into the 125 also then top the rest off with fresh water. im also going to move the fish. and also all the filtration from the 75 to the 125. now my question is will i be ok by doing this? meaning i wont be having to go threw another cycle right?
its just gunna be like one big water change in my eyes!!!

Aggreed.
You wanna make sure the filter capacity is big enough for you new tank.
Elsewise you'd have to add a secondary filterunit.
The BB will grow into the new filter by using the BB from the old one.
Just take care you do not upgrade your bioload.
If only the fish you got now get rehomed, things should be cool.
I did the same lately when I upgraded my 18Gl to a 90Gl tank.
All went schmoove!

ya right now i only got to aquaclear 110s on the 75 that ill put on the 125 but i figure my oscars are still small and my pleco is no more than 3 and a half inches im not putting anymore fish in so i should be fine with filtration for now then add mabye a canister filter down the road when oscars start getting bigger.

Perfect plan Pauly!!! I can't wait to see pics!!!

Spot on paul

Just make sure do it in one go