How would one go about upgrading a tank

[dnas17]

This may or may not be a very stupid question, but I currently have myself a 75 gallon tank that is well established, has been running for a year and has plenty of corals, fish and inverts inhabiting the tank. I am looking to upgrade to a larger tank probably like 125 gallon in that range however I wanna know how exactly I would go about doing this considering the tank would have to cycle etc. I know I would have to buy more sand/dry rock to accommodate for the larger tank footprint but how do I keep all the beneficial bacteria in my tank to ensure all my fish can move from tank A to B safely.

[Aquaticfinatic]

If it's going in the same place set up some containers to put your live stock in. Save as much water as you can. Move your rock and all out of the old tank. Put new tank in place put sand back in rock in then water then live stock. All done in a day ....... Easy! This is the basics to it. Hope that helps.

[dnas17]

It seems so simple in theory but my biggest fear is causing some sort of mini cycle that slaughters my livestock in less than a few hours..

[az]

I would add:           move everything minus the sand, once all in, rinse sand good and add them back to new tank few cups at a time.

[Mike L]

 I'm not a salty so it might be different with freshwater but I just did the same thing with a tank substrate change out and followed the guidelines Aquaticfinatic suggested. I have an overstocked Tanganyikin tank and all is fine.
In fact the parameters have very recently gotten much better then ever before. (Story I would reluctantly share with all if your interested)
It's about keeping the established bacteria alive and supplanting it to the new tank. It's really like doing a water change with a whole lot of steps in between. Also in the end if it is what you want to do just do it. As a member here recently told me. It's all a learning experience. Enjoy it. 

[Stussi613]

The majority of the bacteria is housed in your rock, so as others have said you want to have bins with your heated stable water to submerge them in, along with some circulation.  If you can't do that for any reason you can also put them in a container and cover them with newspaper soaked in tank water.  Depending on the condition of your substrate, you can either rinse it as Az says, or just replace it if you want something different (I have aragonite in my small tank and I'll never use it again!).

It's always easiest to do if you can house the tanks next to each other, but most of the time one comes out and the other goes in its place and moving a 125g setup full of water and rock is not something a couple of humans can actually do.

Good luck and let us know if you need to borrow any supplies, some of us have allot of Rubbermaid bins lying around from redoing tanks...would be happy to lend you some if you need them.

[fish]

Might want to keep a few cups of your existing sandbed to seed the rinsed bed in your new tank. There's a lot of bacterial action in the sand bed as well as the rock.

[Feivel]

Definately rince the sand very well, if not use new sand. Aswell try and keep all your liverock facing the same direction. I.E. Try not to flip them in the bucket and put the underside of the LR exposed to the light.

It definately takes the better part of the day to do this. Depending on the amount of corals you have you may need a few bins. wich would need a few circ pumps and heaters and definately dont forget the whole shelf of towels.

Try and save as much water as possible and use at least 30% newly batched water for the fill-up. Let the sandstorm settle before adding corals/fish try and keep it to a minimum. Make sure all your plumbing is nice and tight, or/and glued inplace, and that overflow boxes are sealed etc...

Rincing the sandbed is a good oportunity to get rid of pesky bristleworm infestations

Hope this helps
Cheers
Good Luck

[bandit]

I've done this a coupe times, I would set up the 125 with new sand and  new rock if you are buying more match temp and salinity to both tanks and connect them together with a pump or fill half way and the rest with yourcurrent tank water.

I prefer the first method after there connected together and all the water has mixed you have all the time to transfer or even wait for the diatom Blume to pass.

[ramblnpony]

I would use "NEW SAND" for sure. Spend the money or you will stir up a hornets' nest with a nitrate and a phosphate spike. You can reuse your old rock with its beneficial bacteria and use some if not most of your old water. Test your water in the days that follow and have a large water change available if needed. Expect some coral shock in the weeks to follow but they should recover fine as long as your new lighting intensity is similar.
Give your fish some hiding places (pvc) in the holding containers and low light to reduce stress. Good luck!