Curing used (and dried out) live rock

[ashwinv96]

Hi all,
I am in the process of setting up my 300 gal display tank. I obtained a decent amount of rock from the previous tank owner. I would estimate ~ 100-125 lbs? The previous guy took his tank of 8 years down and stored all the rock in plastic bins for several months - maybe even a year outside. When I got the rock, it still had a fair amount of what looked like dead organic matter on it.
For that reason, the first thing I did was bleach cure the rock with a 10:1 water to bleach ratio. I only meant to keep it in there for a few days or week at most but ended up getting busy with other things and it sat in there for maybe 4-6 weeks. When I took the rock out and after rinsing it, I noticed that a few long shelf-like pieces and certain other kinds of rock became pretty soft - soft enough to where i could split it into rubble with a slight whack with a rubber mallet. Some of the other pieces are still hard. Here are some pictures below AFTER the bleach cure of the solid rock and the pulverized rubble that I have.

What should I do next? Should I keep the rubble? The rock looks much cleaner but still has some stuck on sand and other debris that is discoloring it.

This is what I was thinking:
1. Pressure wash the rocks (not rubble).
2. Put rocks and rubble in a plastic kiddie pool with heated saltwater to begin a natural cycle. (not in a rush and this could take 3+ months)
3. In the meantime, start my tank with about 100 lbs of dry rock and fresh live sand

Appreciate all your inputs and Happy New Year 2025 to anyone reading this!

Rock after bleach cure

 

[Tamberav]

I re-used some old rock, I just did a bleach soak, freshwater and prime soak, then let it dry out, then tossed it in with some Fritz 9 and used it.

Whether you keep the rubble is.. do you want rubble? I only use it to mount corals to instead of ugly frag discs but some people keep it for cryptic zones or such.

 

[Fish Fan]

I re-used some old rock, I just did a bleach soak, freshwater and prime soak, then let it dry out, then tossed it in with some Fritz 9 and used it.

Whether you keep the rubble is.. do you want rubble? I only use it to mount corals to instead of ugly frag discs but some people keep it for cryptic zones or such.

I agree, when I see previously used rock like that, I also have done a bleach cure. When complete, if you let the rock fully dry, any residual bleach will be inactivated. I think this is the way to go, you want to rid the rock of any old organics that will basically just rot in your new tank.

I've never experienced the "softening" of the rock you're seeing, so I'm not sure what's going on there. I can tell you I've soaked rock in a bleach solution for many weeks total, and that didn't happen.

I'm not so sure you got all the organics off that rock. I don't know the "real" concentration you would need, but if you used household bleach and mixed it at 10:1, that's not a whole lot of total chlorine to remove all the organics from the rock. If you don't have enough chlorine, it will simply be exhausted before all the organics have been oxidized.

My quick rant on bleach, because I think this is everything that's wrong with the United States right now , and it's not new, this started years ago lol!

It was not all that long ago that typical household bleach like Chlorox was about a 10% or even 12% solution of sodium hypochlorite, the active ingredient. Overtime, the concentration of the solution has slowly gone down, to now some of the "budget" brands can be as low as 5% or 6%. All while the price has gone up. And now lately, it's not even a gallon of bleach anymore, it's 121 fluid ounces. <Notice that dirty little trick.

So here's the real kicker with bleach specifically: Not only are you paying more than ever for the product, but you're getting a smaller volume than you used to, and the concentration of the product is much more diluted. Because it's more dilute, you need to use more to get the same effect as you did with "the good stuff" from years ago.

You add all that up, and the end consumer is getting screwed in every possible direction. And the people who make the bleach and the people who sell the bleach don't care at all. <<That's the problem.

Why am I so fired up about bleach? Because I have a modest swimming pool, and my preferred way to sanitize it each season is with liquid pool chlorine, which is the same as bleach, just stronger. And I go through A LOT of it in a season. The pool chlorine used to be 16% or 18%, and now it too has gone down to 8% or 10%. One store near me still offers a 12%. To sanitize my pool I have to bring the chlorine to a certain level. With weaker solutions I have to use more bleach (liquid chlorine) than I did in the past. And, I have to physically haul more jugs out back every year.

There's my bleach rant, sorry it's so long and for partially derailing :-)

But to bring it home, when I bleach cure old rock I use swimming pool liquid chlorine because it's stronger, and I mix it much more like half and half to water. Once, I did a small amount of rock in a 5 gallon bucket and used straight pool chlorine, though I don't know if that was a good idea. I think "some" water is beneficial. This is just my experience, I'm not a chemist; be safe, wear eye and skin protection, work outside, wear a respirator, etc.

Huge long story short, I think you need a longer soak time and/or more bleach to water. The rock should be fairly bright and white again when done.

 

[ashwinv96]

Thanks for the suggestions! Especially enjoyed the aside on bleach :)
Think I'll give the rocks a longer soak in swimming pool liquid chlorine and probably just live cure and cycle the rock and rubble before tossing it in the tank.

 

[reefer10]

Ok so I did a SUPER long bleach cure. Forgot about the bucket for several months. It was dried live rock. The rock in question I believe was from Jakarta. It had a lot of organics on it. After the long bleach cure I saw some black stuff on the rock, maybe was there before. So I did another bleach cure a couple times, more correct timeframe. Black is still on the rock. It is smooth and does not scrub off. Almost like black coralline. Other ricks in the same container did not have this happen. Couldn’t be mold right lol?

 

[reefer10]

 

[reefer10]

 

[reefer10]

I thought for a bit it was the rubber from the suction cups on the pump that had disintegrated a little and deposited, but it won’t scrub off with a toothbrush.