Substrate in the fuge?

[HighChiefKC]

I ran miracle mud on my 180 12 years ago. What’s the strategy now? Do I need any kind of sand or substrate in the refugium? I plan on only having chaeto in there. I have a couple of small bags of brightwell koral lagoon substrate. Wondered if it was ok to use that or best not to use anything?

 

[Idoc]

Some still run miracle mud as a substrate... some sand... some live rock rubble... so many options, and they all seem to work well.

 

[F i s h y]

I like the crushed coral and shells personally (larger peices) . Lots of room for pods to run around and lots of surface area for bacterial growth.