Cycling New Tank with Cured Live Rock and Live Sand


Reefing newb
Hello Reef Experts!

Although I have had a long-term fascination with saltwater tanks, I only recently committed to getting a system. After a whole bunch of research, I was only more drawn to the idea of a coral tank as I now see the aquarium as a 75 gallon biology lab that presents a lot of scientific and technical challenges.

So, my set up is...
75 gallon reef-ready
Sump with skimmer and refugium
Cured live rock (LFS said it had been in their curing tanks for at least two weeks and the rock does not smell bad)
Live sand from CaribSea
Two simple powerheads (The vortechs sounded great, but a little pricey!)

The tank is all set up and aquascaped. I have also added most of the sand.
Here are my questions;
With the "cured" live rock and live sand, I believe that I have a complete set of ammonia eating and nitrite eating bacteria. The rock has been in just under 24 hours, and ammonia, nitrites, and nitrates remain at 0.
1) Am I right that the bacteria cultures are all set?
2) Because there was so little die-off on the live rock, do I need to "feed" the bacteria while the tank is settling?
3) What should I "feed" the bacteria? Being fascinated by the science side of this, I'd love to slice up a shrimp and through it in, bit by bit, but I don't want to foul up the set-up.

Thanks for the help. A picture of my set-up is attached.



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First, that's going to be one beautiful tank once finished. Great rockscaping. With my tank, I put in all my live rock but wasn't seeing any readings showing the cycling process. I got some help from this site and I cut up half a shrimp and tossed it in (only half for me because I have a small tank). I let that stay in there for a while with my powerheads going and instantly saw Ammonia and Nitrite activity. Me being a bit paranoid though, I took the remainder of the shrimp out after a few days and let it do it's work from there. The process went very smooth for me from there so I would suggest the shrimp idea as well.

I have also heard that just putting in the live rock will start the process so you might be all set where you are.

Patience is key when cycling a new tank.
Welcome aboard! That aquascape is sweet! Can't wait to see more. It wouldn't hurt to throw a little shrimp in there to feed your bacteria population and see what happens.
Very nice looking! I agree to throw in a piece of raw shrimp from the grocery store. You may see your ammonia and nitrites rise in reaction to that. Once they go down to zero, then you can be confident that your tank has cycled. Until you test it out, you don't know though.
I added part of the shrimp yesterday afternoon and Ammonia and Nitrites remain at 0. Before placing the shrimp, my nitrates had shot up pretty high, but they are coming down. I think the drop in the nitrates is because of the Cheato in the refugium, right?

Thanks again for all the help!
I could use some input from some of the more experienced out there. Today is day 8 of my new aquarium cycle (with cured live rock and live sand) and I am not sure if I am sure of what to make of my testing results.

This is what is going on;
Ammonia: "Spiked" at 0.25 on day 2. Has been 0 since.
Nitrites: 0 since Day 1
Nitrates: Spiked at 20ppm from day 3 thru day 5. Have dropped to 10ppm
SG: 1.024
PH: started at 8.3 and has declined to 8.0

On day 2 I added part of a table shrimp. On day 6 I added the rest of the shrimp. Today (day 8) I removed what I could of the shrimp, as it had degenerated to slime. There are plenty of shrimp-bits in there. Gross.

My protein skimmer is finally producing some scum. About 1/4 an inch in the cup that was produced last night.

Some orange and brown algae are beginning to grow on the live rock, although they are both very limited.

Cheato in fuge seems to have some new growth.

1) Is my bacteria already in place and ready for a real (small) bioload?
2) I didn't expect the pH drop. Why might that be happening?

Thanks for any help.
Don't run the protein skimmer during the cycle. There is no need at that point.

I'm not sure if you cycled or not but I'm leaning towards yes. You should have seen more than a .25ppm ammonia spike and you definitely should have seen a day or two of elevated nitrites even if it's just a little bit.
Still, because you used cured rock and sand you may have skipped or missed the cycle. The safest way to test this would be to get another table shrimp and drop the whole thing in (get one unpeeled from the grocery store and they're easier to remove later). Let it sit for a couple of days. If you still don't see any spikes you're ready for a fish.
In all honesty, if you didn't see much of a spike you're probably ready now. A hardy fish would survive. The biggest worry is that the bacteria you did have is having some die off because of a lack of bioload. Like anything else, ammonia eating bacteria need ammonia to survive...but as they die and produce ammonia the populations balance each other.

pH drops naturally at night and rises slowly during the day reaching its peak before the lights go off.

And by the way, I LOVE your aquascape. It is going to look really cool!
Personally I would give it a few more days but I think that you are good to go.
As far as the PH drop it is normal for the PH to fluctuate during the day so don't worry about it. A reading of 8.0 is perfectly acceptable.