Down sizing tank

[puffer_reef]

Hi all,

I have a 40 gallon that I am downsizing to a 20 gallon. Would it be a better idea to take the sand out of the 40 and use it for the 20 and take the old tank water and put it in the new tank with 2 of the live rocks, or just cycle the 20 with new sand and new water?
Thanks in advance!

 

[Gedxin]

You can reuse sand, though you should probably rinse it with RODI to clean of excess detritus.

You can take old water and put in new, but there's not much reason other than 'water savings.' Your bacteria doesn't live in the water column, that's all on your rocks/sand.

 

[Jekyl]

As long as you're moving the rocks over new sand and water won't mean you have to cycle again. The rocks are what matter.

 

[puffer_reef]

Okay cool thanks guys!