Cycling a new tank and fresh live rock

ICoelho · 2024-12-21T10:37:44-0500

Hey! I'm pretty new to the saltwater side of the hobby and can't find any information about my specific situation, so I appreciate any help.

So, about two weeks ago, I got an used 60g tank that had been running for a while and was really well-established, albeit a bit neglected. I've moved all the live rock from that tank plus the two damselfish that were in it into a bare bottom 25g with a HOB filter while I restored the main tank and bought/waited for the supplies to arrive, so the rock never dried out (there's a lot of it too, as you can see in the picture). Haven't got an ammonia spike in this placeholder tank, undetectable nitrites, extremely low levels of nitrates, and the fish seem to be doing well, so I'm assuming the rocks are nice and healthy and took care of the "cycle".

So, now it's almost time to set the main tank back up again. I went with Aqua Medic's bali sand, which is made of dry limestone, and I'm a bit confused about how all those factors will play into the cycle of the "new" tank.

- What is the safest procedure here? Set up the tank with the live rock and the new sand and wait for the sand to be "cycled" before I add the two fish in, or is the live rock enough to avoid ammonia spikes?

- If waiting is the best choice, will the fish be ok in the 25g tank with just the HOB filter while I wait?

I also have Dr tim's nitrifying bacteria that can be dosed in both tanks if needed, f.ex. if it would make it safe to move the fish to the main tank once it's set up or if it would help keep them safe in the 25g while the other tank cycles.

Sorry if it sounds like a stupid question and thanks in advance!

PotatoPig · 2024-12-21T10:43:38-0500

The live rock is already cycled, and the addition of the sand won’t uncycle it, so if you put it in the new tank the new tank will be cycled immediately.

One comment on the sand: For a while it’ll absorb phosphates as they’ll bind to it. This isn’t a problem, but until that process reaches an equilibrium you won’t be able to reliably measure what your phosphate production is and may go through a period of very low phosphates, followed by a brief period of unstable phosphates, that could be a challenge if you plan to immediately add corals.

ICoelho · 2024-12-21T11:08:04-0500

PotatoPig said:
The live rock is already cycled, and the addition of the sand won’t uncycle it, so if you put it in the new tank the new tank will be cycled immediately.

One comment on the sand: For a while it’ll absorb phosphates as they’ll bind to it. This isn’t a problem, but until that process reaches an equilibrium you won’t be able to reliably measure what your phosphate production is and may go through a period of very low phosphates, followed by a brief period of unstable phosphates, that could be a challenge if you plan to immediately add corals.

Thanks for the answer! I wasn't planning on adding corals right now, but I was flirting with the idea of getting a condy anemone once the levels were stable enough. Do you know if this phosphate fluctuation would disturb it too much? I don't mind waiting