Jump start new tank from old?

So I have a 100g tank thats cycled, many fishies, a some softies and I've decided to also started a 29 gallon tank since i have all the equip i need...

I was curious if i could just start this tank by using 20 gallons from the 100g tanks water change. also stealing some rock and sand from it. So basically i would be looking at 20g of old and 15 of new water to go into the tank initially(gonna have a 10g sump).

What could I expect from this?
Im hopeing that maybe after a week i could add some fishies, start collecting the live rock? I dont really want to cure anything for this tank, it would be stricly picking out rock ready to drop in, its secondary purpose is to be a place for all the stuff in my 100g that i no longer want. ie texas holy rock being replaced, maybe smaller fishies that are getting picked on, or just to make room for something new...


Dan

 

I think you would still get a small cycle, not saying you couldn't do it.
Why not just do it and wait a few weeks to move any livestock over and see if the amonia spikes?

 

You should not have any spikes at all if you do it that way.

I just started my 200g reef from my 90g reef with no spikes of any of the nasties.

The worst you should have is a little cyano, diatoms or similar, but it will pass.