Adding a fuge

[brotox]

I was thinking of adding a 10g refugium to my 20g tank, mainly for more water volume. It is a fairly new tank, just finished cycling about a month ago. I only have a small clean up crew in it now. My question is, if I add dry sand and base rock, do I need to cycle it before I hook it to the main tank? WIll it cause a spike if I don't add any more live rock or sand?

 

[acekjd83]

the very precise and scientific answer is.... possibly

bacteria will break down whatever organic matter is left in the dry sand and rock (if it was previously live...?), releasing wastes into the water.
on the other hand, if the rock and sand were not live before (i.e. sand from home depot and mined live rock) then a good rinse will clean off any dust and debris, and there should be no organic matter to be released in the first place.

 

[bang guy]

It won't need to cycle. If it's aragonite sand I'd suggest curing the sand and rock first though.