Upgrading tanks

[Wolf89]

I have a 20 gallon long with 20 or so pounds of live rock. It has 3 fish, and some coral (soft coral plus a favia, 2 montis and a digi) I am putting new dry sand plus 80-90 pounds of dry rock into my 90 with 40G sump. My question is, since the rock in the 20 is already supporting what I have, can I transfer it all to the 90 and just increase feedings to I can add more fish

 

[James M]

You should cycle the 90 first and then transfer everything over once it’s done

 

[Eagle_Steve]

I second what @James M said. The dry rock, depending on what kind it is may leech phosphates or old organic matter. Best to deal with that with no live stock in the tank. If it was 1 or 2 rocks, maybe OK, but that much rock could not be good if it happens.