Yes a Refugium or holding tank or a save that coral from that damn nippy fish tank.. Most sumps I see have a lot of upper space waste so I've been making my sumps with these upper ranks to hold live tick macro whatever you like
And the space below the mini tank is all return so if you don't have an auto top off you have more room before you have to top off
Both my 180 and my 50 I can go away for a max of 6 days before top off if not using an ato
I hope this helps did the same here for my 50
And my 180
