Re-Curing Old Rock

[Biokabe]

I'm in the middle of preparing for a tank transfer, and as there is a bit of a volume increase, I'd like to add some more rock to the tank. Obviously it's easier to add that rock when I'm setting up the new tank, and as luck would have it I have about 30 pounds of extra rock lying around.

But as luck would also have it, that rock was from my very first tank, which took a lot of abuse from me. No copper or heavy metals in it, but I'm sure the rock is loaded with old, decayed life and all the phosphates and everything involved. Additionally, it's been sitting in my garage, dry, for about 10 years now. So it's had 10 years to pick up dust, sawdust, webs, and everything else that's happened in that garage (paint drying, wood stain drying, etc).

I know it's not really live rock any longer, but it was really good rock - I picked it up before all the restrictions on Pacific rock were put in place, and there are some great shapes in there. But I don't know everything that is currently absorbed into the rock. Is there a treatment I can do to the rock to get it back to a useable condition?

 

[Fish Fan]

If the rock was once live, and has now dried out, I'd suggest doing a bleach cure to quickly remove all the organic material:

Bleach Curing Dry Rock for a Saltwater Reef Tank - BRStv Reef FAQs

There are three main methods for curing live rock for a saltwater reef tank: natural, bleach and acid. Our focus today is using bleach for curing dry rock and we answer three direct questions. 1. What is a bleach cure? 2. When is it appropriate to bleach cure rock? 3. How to do

www.bulkreefsupply.com

 

[lapin]

Pressure wash it. Soak it. Test your soaking water for nutrients. This can be fixed. Above. You can also throw in one of those heavy metal absorbent pads. Unless it’s beyond repair it should be fine

 

[Mr. Mojo Rising]

Agree with above, I bleach all my old rocks and re-use them.

 

[Biokabe]

Do you need heat, water movement, or aeration, or just chuck it all in a container and let it cook?

For off gassing, I assume that I wouldn't want to cover the container? And I also assume I wouldn't want to keep the container in a closed shed with limited ventilation?

 

[skey44]

I had old live rock from the 2000’s dry in my yard. I did a thorough saltwater curing process in a brute can with water changes, bacteria dosing, and aggressive phosphate removal. Bacteria are omnipresent, you likely don’t need to add them from a bottled source. I knew this but fell victim to the marketing. The rock was leaching phosphate, I verified this with Hanna testing. The phosphate removal step is unnecessary unless you have bound phosphate in your rock like I did. Many people who use dry rock actually have to add phosphates too. I let it the rock “cook” (cooking is a term for dark curing, do not actually cook rock!) in the dark for 3 months before the tank was wet. It worked out pretty well until I let my nitrates bottom around zero for too long and got Dinos. I think if I had been more proactive with a nitrate or ammonia dosing regimen I would have avoided the uglies all together. I did also introduce a robust clean-up crew once the lights came on. I have incidentally introduced various forms of algae and invertebrates to my system from frags that need some control even with nutrient regulation.
I think this process would have worked for other dry rock too, but I prefer the shapes and porosity of the old live rock to the current dry rock I’ve encountered on the market.
Good luck finding the right rock for you. Dark curing is a good idea IMO. I still add some bottle bacteria to my tank, but it’s mostly because I see extreme polyp extension afterwards, not because I think I need it for nitrification or stability.

Copy pasted from a recent post on my build thread where I addressed exactly this.

 

[skey44]

Do you need heat, water movement, or aeration, or just chuck it all in a container and let it cook?

For off gassing, I assume that I wouldn't want to cover the container? And I also assume I wouldn't want to keep the container in a closed shed with limited ventilation?

I just placed the old rock directly into saltwater after a quick rinse/scrub to remove any easily removed organic matter. Used a Brute with circulation and lid on. Changed water a few times 100% until it was cycled, then used GFO to remove the leaching phosphates until I was satisfied.
It’s been the best rock I’ve ever had all over again.
I did let it sit in the brute curing for approximately 3 months as I was waiting for my tank.