Cycling Help Needed

[icehood24]

I am planning to be cycling a new tank, since mine right now was done wrong and is unsavable. I want to cycle with live rock (not dry rock) and have some questions. Would I be able to cycle it with a live rock with coralline algae? And if so would it be better to order online (since my lfs doesn’t have any live rocks for sale with it)? Would I need to keep tank lights on for the cycle or turn them off the whole time? Please help me!!

 

[blaxsun]

Yes, you can use live rock to setup your tank and skip most of the cycle (since they typically come with the bio filter preserved). So that's the upside - the downside is any potential hitchhikers that accompany the live rock.

You can also insta-cycle dry rock with products like Instant Ocean Bio-Spira and add fish right away (this is more expensive than the traditional cycling method, which is why most don't use it).

 

[jda]

First, there is curing of live rock and there is the nitrogen cycle. We need to be sure and not mix terms.

Coralline algae will survive the curing of the live rock. So will most of the microfauna. Some of the macrofauna like corals, some algaes, etc. might die off in the initial curing or over time since not all of it is able to live in captivity for long (especially most filter feeders). This is what is supposed to happen and you still end up with the good things on the rock.

Basically, curing is getting the rock stable with all die off gone.

The nitrogen cycle needs to be understood a bit differently when using live rock. When using cured live rock in a new tank, it can very likely handle fish waste (ammonia, nitrite and maybe even some nitrate), but your tank is not really cycled yet. The cycle still needs to happen where all of the surfaces, filters, sand, whatever, get into the action and the tank truly becomes dynamic. Until this cycle is complete, you need to be really careful not to overstock nor overfeed while the rock alone is handing fish waste. It is also really important to remove any die off that happens - corals purchased too early, dead fish, more stuff dying on the live rock. Keep that bioload low. As long as you remember that just live rock processing some waste is not as good as a whole ecosystem doing it, you will be fine. The rock can allow you to start up a bit early with some things like fish, but your tank will not be dynamic enough to overcome any impatience or over feeding, so be smart.

The last part of the nitrogen cycle is having anoxic bacteria turn no3 into nitrogen gas. Your rock can do some of this. A sandbed of decent depth like 2 inches or more, can do this too if you don't disturb it too much. Most don't even know about this part of the cycle and think that just keeping fish alive is all that matters, but it is important. This will come, so just be aware of it for now and don't worry about it yet.

I have no opinion on lights off or on. I always had mine on since my live rock had things that need light. Algae will come, but it is coming anyway. I also like to be able to see the live rock to see if anything needs to come out. To each their own.

I wrote more about live rock here a day or two ago. I might help some:

Live Rock Cycling Question

I see there have been a number of similar threads (so apologies for the duplication) but I'm not sure I see a clear answer. I am converting my long time freshwater discus tank to my first saltwater tank (125 gallon). I intend to add 100 lbs of the premium deco live rock from Gulf Live Rock. I...

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