Adding a 2nd tank to a system. Re-cycle?

[atomic081]

Hey all, Thanks in advance for any advice.

So I'm helping a buddy with a new tank build. He currently has a 220g with a 50g sump. We are adding another 220g to the system and upgrading the sump to a 100g that will run both tanks. The new 220 will be a bare bottom predator tank. The thought was to run the new Predator tank with very little rock. So essentially he is just adding water volume and 50 lbs of rock to a preexisting 275g system.

Will this cause the whole system to start another cycle. We have the option of not connecting the 2 systems until after a full cycle has happened, but our LFS said to just add it all from the start.....any opinions?

Thanks!

 

[Rubberfrog]

It will be fine. Don't add 57 fish the first day.

 

[Greg P]

Unless you add live rock with die-off, it shouldn't cause a cycle. Once more fish are added there will be mini cycles.
Adding minimal rock to the second tank will require the existing tank to pick up the nitrogen cycle load.
Predator tanks can get messy resulting in high N&P. Be aware of that if the existing tank has corals as it will mess with it's current balance.

 

[Super Fly]

Be aware of that if the existing tank has corals as it will mess with it's current balance.

+1 on this bc of new sump. The sump, equipments and pipes contain beneficial bacteria so adding a new sump may cause mini-cycle AND adverse coral reactions, which happened to my tank when I replaced the sump. Some corals didn't like the new sump and remained closed for few weeks.

 

[Super Fly]

forgot to mention, wish I had wife approval for even just one 220G tank... so jelly

 

[AdamH300]

forgot to mention, wish I had wife approval for even just one 220G tank... so jelly

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