Cooking Rocks - When Are They Done?

bzb

bzb

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With all this baking and grilling and everything else going on, who's cooking rocks?

When you get the rocks from a known source, how long do you cook em? To be clear: cooking rocks for me is using water change water, circulating in a bucket with a powerhead.

I did my original dry rock for over a month, but it was "fresh" saltwater. Not sure what the best protocol would be to introduce these into my DT when I'm using the tank water.
 
"Cooking" rock is when you nuke it with bleach, acid or peroxide.

"Curing" rock is the preaging of the rock. This is done with freshly nuked or dry rock. This preaging is done in saltwater with an ammonia source to start the nitrogen cycle and seed all the rock with bacteria. This process takes the same amount of time as it would if you were cycling a new tank, 4-6 weeks.

What you have is "Live Rock" if you got it wet and it's already seeded with bacteria. There's still usually some die off when moving live rock. Generally you keep it in it's own container of saltwater with circulation and heat the same way you'd do when curing. You monitor Ammonia, nitrites & nitrates. When the 1st two are zero and you have nitrate you're good to go. Time would be a week or two in most cases. This is also a good time to monitor it for any undesirable hitch hikers.
 
I like MarcoRocks just because I know what I’m dealing with. As Adam mentioned, you can seed the rock using ammonia, though I do like to add a bacterial supplement to kick things off.

As for using live rock, just be careful with that. If transferred right over to a display, even if left fallow in saltwater, you can & will get hitch hiker organisms. Everything from bacteria to algae and perhaps other higher life forms, good or bad. Once there, many may be difficult or impossible to remove, without a tear down.

If using pre-used dry rock, you may not know where it came from, or it’s history? Regardless, it’s a safe bet to have significant phosphate, as the deposition of soluble phosphate on coral rock is thermodynamically favored, chemically speaking. It forms the highly insoluble calcium phosphate, which may leach phosphate slowly back into the water later. If you are set on using it, I would give the rock a couple of good soaks in a 5% citric acid solution. Followed by several soaks in DI water. The citric acid will help remove any phosphate and nuke all stragglers. The DI water will help remove residual citric acid afterwards.
 
Adam said:
"Cooking" rock is when you nuke it with bleach, acid or peroxide.

"Curing" rock is the preaging of the rock. This is done with freshly nuked or dry rock. This preaging is done in saltwater with an ammonia source to start the nitrogen cycle and seed all the rock with bacteria. This process takes the same amount of time as it would if you were cycling a new tank, 4-6 weeks.

What you have is "Live Rock" if you got it wet and it's already seeded with bacteria. There's still usually some die off when moving live rock. Generally you keep it in it's own container of saltwater with circulation and heat the same way you'd do when curing. You monitor Ammonia, nitrites & nitrates. When the 1st two are zero and you have nitrate you're good to go. Time would be a week or two in most cases. This is also a good time to monitor it for any undesirable hitch hikers.
Click to expand...

Good callout. I did actually soak them in bleach solution overnight, then left it all in the sun for a couple days. So yeah, I guess curing, not cooking. But Imma still cook em!

That's what I was kind of figuring: a couple weeks. Didn't know if there were any other telltale signs that they're ready to be introduced.
 
ichthyoid said:
Regardless, it’s a safe bet to have significant phosphate, as the deposition of soluble phosphate on coral rock is thermodynamically favored, chemically speaking. It forms the highly insoluble calcium phosphate, which may leach phosphate slowly back into the water later. If you are set on using it, I would give the rock a couple of good soaks in a 5% citric acid solution. Followed by several soaks in DI water. The citric acid will help remove any phosphate and nuke all stragglers. The DI water will help remove residual citric acid afterwards.
Click to expand...

That is EXACTLY what I'm trying to avoid here. I'm already coasting at 0.1ppm on phosphates, so would prefer to keep it out of anything I'm introducing.

It's been in my used tank water for almost two weeks. I just ran a phosphate test on it, and wouldn't you know... it's at 0.1ppm. Hmm.

Should I dig it out and give it a soak in citric acid instead of continuing on?
 
bzb said:
Good callout. I did actually soak them in bleach solution overnight, then left it all in the sun for a couple days. So yeah, I guess curing, not cooking. But Imma still cook em!

That's what I was kind of figuring: a couple weeks. Didn't know if there were any other telltale signs that they're ready to be introduced.
Click to expand...
The rock is dead, so 4-6 weeks curing.

bzb said:
That is EXACTLY what I'm trying to avoid here. I'm already coasting at 0.1ppm on phosphates, so would prefer to keep it out of anything I'm introducing.

It's been in my used tank water for almost two weeks. I just ran a phosphate test on it, and wouldn't you know... it's at 0.1ppm. Hmm.

Should I dig it out and give it a soak in citric acid instead of continuing on?
Click to expand...

I would, that'd be your bet bet for getting the PO4 down.
 
If you’re trying to avoid introducing a bunch of nutrients, then you may want to cook them in a strong acid first. This will dissolve any of the organics, and a bit of the rock.

when I last used a 10% muriatic acid on a large batch of pukani rocks, for a 15 minute bath, I noticed an 11% decrease in dry rock mass. I measured each rock religiously at multiple times. The 11% decrease was surprisingly constant across-the-board.

just be cautious and take lots of precautions. Muriatic acid is extremely strong. After that, you can begin the curing process
 
Another safer, but much slower, process is that you can simply cure it to accomplish this, as others have suggested. And do a bunch of 100% water changes. If I were to do that route, I would not use saltwater at first. I would start with freshwater, and save myself the slight expense.

once it has been going for at least several weeks, then I would switch to saltwater from my water changes.

Additionally, if you put a protein skimmer in the bucket that the rocks are curing in, you could use lanthanum chloride to help bind with the phosphate, which would then be sucked out by the skimmer.
 
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ActiveAngel said:
If you’re trying to avoid introducing a bunch of nutrients, then you may want to cook them in a strong acid first. This will dissolve any of the organics, and a bit of the rock.

when I last used a 10% muriatic acid on a large batch of pukani rocks, for a 15 minute bath, I noticed an 11% decrease in dry rock mass. I measured each rock religiously at multiple times. The 11% decrease was surprisingly constant across-the-board.

just be cautious and take lots of precautions. Muriatic acid is extremely strong. After that, you can begin the curing process
Click to expand...
As Bill @ichthyoid said above, citric acid is the best for removing Phosphate and it won't dissolve as much of the actual rock.
atlantareefclub.org

Heeeeelllllpppppp with No3 and Phos

Really interesting! I'm in 31029 though, so no telling when I'll get back up to atl It’s cheap to build. And it works really well.
atlantareefclub.org atlantareefclub.org

ActiveAngel said:
Another safer, but much slower, process is that you can simply cure it to accomplish this, as others have suggested. And do a bunch of 100% water changes. If I were to do that route, I would not use saltwater at first. I would start with freshwater, and save myself the slight expense.

once it has been going for at least several weeks, then I would switch to saltwater from my water changes.

Additionally, if you put a protein skimmer in the bucket that the rocks are curing in, you could use lanthanum chloride to help bind with the phosphate, which would then be sucked out by the skimmer.
Click to expand...
I went that route with Lanthanum when I started my 1st system. The problem is Lanthanum with only take care of the Phosphate that has dissolved out of the rock, not what it still bound in the rock. I battled PO4 from all the Pukani I used for quite some time after the tank was up and running. I'm going with citric acid this time.
 
Last edited:
I use citric acid for the following reasons-
-it is a weak organic acid, with a unique ability to specifically solubilize phosphate bonded to calcium
-if the citrate does react with calcium, the calcium citrate formed has very low solubility.
-using a weak organic acid limits the amount of rock degradation that will occur.
-any remaining citrate in/on the rock will be metabolized by bacteria, as it is an organic compound.

Muratic acid is a solution of hydrochloric acid, which is a strong mineral acid. Typically it is diluted to about 10-30% strength for sale at retail. It’s use also also leaves chlorine as a byproduct.

In short, the muratic will work faster, but with loss of rock, as mentioned.

The citric is more specific, but also slower.
 
Adam said:
As Bill @ichthyoid said above, citric acid is the best for removing Phosphate and it won't dissolve as much of the actual rock.
atlantareefclub.org

Heeeeelllllpppppp with No3 and Phos

Really interesting! I'm in 31029 though, so no telling when I'll get back up to atl It’s cheap to build. And it works really well.
atlantareefclub.org atlantareefclub.org


I went that route with Lanthanum when I started my 1st system. The problem is Lanthanum with only take care of the Phosphate that has dissolved out of the rock, not what it still bound in the rock. I battled PO4 from all the Pukani I used for quite some time after the tank was up and running. I'm going with citric acid this time.
Click to expand...

Funny - I remember that thread because it was right when I got restarted. I didn't have citric acid on hand at the time, so I just did bleach and a soak in diluted vinegar for a few days before curing them in fresh saltwater.

Any suggestions on citric acid available right now?
 
I totally agree. That’s why I mentioned that muriatic is the very fast approach. I agree citric is much safer, and I would recommend it. However, I don’t have data back it up, so I cannot give you any percentages for citric that answer your question.

The only part I’m uncertain on is that citric acid won’t dissolve much of the rock. I’m not sure if this is true. I just don’t know. However, I would agree that any rock that it does dissolve will be at a slower rate. If I had to guess, I would say that the amount of material (organic and rock) that is dissolved is proportional to the amount of acid present and it’s strength, and that the divided proportion between those two categories (organics and rock) would be divided relatively equally between both acids.

Nonetheless, I agree. Citric acid is a better choice for all the reasons listed by @ichthyoid . While not as fast as muriatic, it’s still extremely fast relative to other options that were previously discussed (i.e. curing with no lanthanum and no skimmer) to remove phosphate.

As for Lanthanum, I agree as well. that’s why I mentioned it is the very slow approach. If you’re using that approach, you’re looking at weeks or months. You would use it during your curing process and waiting for the phosphates to break down naturally into the water, and the lanthanum and skimmer to remove it. .... It takes a looong while. But, depending on your values, it may be the choice that best fits your needs. That’s for you to decide.
 
ichthyoid said:
So, just curious, what was 100 lbs used for?

I don’t order that much for my lawn! ;)
Click to expand...
I've got 400lbs+ of rock to cook, a 220 tank to clean, a 150 sump, a 90 sump, several pumps and other equipment...
I was hoping to have some left when I'm done but I'm not so sure. :rolleyes: o_O
 
@ichthyoid Remember I have a 500 gallon 96x48x29 on order. Gonna take some rock to scape...
I've got a lot of used Pukani too. Seeing as you can't get it anymore I bought what I could and plan to clean it well.
20200119_133703.jpg
That's a 150 trough holding about half the rock I have.
 
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