Mixing old with new?

[bct15]

I'm finally about to set up my new tank this Monday and get all of my stuff out of these storage bins and tiny tanks. I was wondering though, will the new tank have to cycle? The live rock and sand has been in storage bins and fish tanks with powerheads and heaters (and water), and I will be using about 75 gallons of the old water and 100 gallons new water (estimate +\- 50 gallons). Do I need to let the completely tank cycle or since it is all established for a long time live rock and sand can my fish be added in about a week or so?

I know that the only way to know if the tank is established is test the nitrogen components of the cycle but wondering what everyone else knows so I clan plan the move over better.

 

[nolen502]

When i started my 34g tank 24 days ago I used 15 gallons of water from an established aquarium and live rock from another and had coral and fish two days later. Never had a problem and all livestock is doing great.

 

[nolen502]

But i know all every system is different so maybe i just got lucky

 

[gparr]

I'd be very hesitant to re-use the sand unless you wash it thoroughly. You might use some of the live sand as "seed" sand for the clean sand bed. Too many strange thing get released when you disturb a sandbed that has any depth to it.

Rock should not be a problem, though I'm a cautious person and would assemble the rock in the new tank and let it run for a couple of weeks with good flow to make sure you aren't going to have any problems. If it's established rock, I would think any type of mini cycle would come and go in a couple of weeks. Regardless of what you do, consider running ample amounts of carbon changed weekly for the first month.
Gary