Question Can I Put These Rocks In My Freshwater Tank?

92Hughes92

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My girlfriend and I recently went to Hawaii. While there and snorkeling I grabbed a couple rocks. One I found off a resort, and another few I grabbed from the Black Sand Beach.

I took them home, boiled them for 10 minutes, scrubbed them, then boiled them for another 10 minutes.

Is it ok to add them to my tank without killing my fish?

Thanks! Pics of rocks below
 

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JessicaSwanlake

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I wouldn't, especially since those aren't from a freshwater source. There are tons of organisms that can survive being boiled for short periods of time.
I think it's better safe than sorry, but if you really want to use them I would soak them in bleach and then maybe boil them again for like an hour or longer and then let them completely dry out for a few days. You might end up having them leach minerals into your tank though, so I would be prepared for that.

Actually, since these are porous rocks, I would scratch the boiling part since they could have air pockets and could explode. If you bleach them just rinse them and soak them in dechlorinated water with added dechlorinator.
 

MikeRad89

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JessicaSwanlake said:
Actually, since these are porous rocks, I would scratch the boiling part since they could have air pockets and could explode. If you bleach them just rinse them and soak them in dechlorinated water with added dechlorinator.
They've already been boiled.

They're completely safe to add as is.
 

Fanatic

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I personally do not see why these rocks wouldn't be safe.
 

Nobote

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Vinegar test them, if they domt react yer good to go,
 

86 ssinit

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I don’t think they’ll be a problem. I use ocean rocks in all my thanks. I have a plant tank and they go in there first. I leave them for a month or till I’m ready to put them into another tank. Never had a problem.
 

ystrout

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They should be fine. If you're worried, pour some vinegar or acid on the rock to test for carbonate minerals that will affect PH/KH. If the rocks don't bubble/fizz, they're fine to use.

The black one looks like lava rock, which is perfectly fine to use. Idk what the tan one is made of, so the vinegar/acid test will help.
 
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92Hughes92

92Hughes92

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ystrout said:
They should be fine. If you're worried, pour some vinegar or acid on the rock to test for carbonate minerals that will affect PH/KH. If the rocks don't bubble/fizz, they're fine to use.

The black one looks like lava rock, which is perfectly fine to use. Idk what the tan one is made of, so the vinegar/acid test will help.
Tested with distilled vinegar, apple cider, and red vinegar. No fizz with any of them. Should be good?
 

ystrout

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92Hughes92 said:
Tested with distilled vinegar, apple cider, and red vinegar. No fizz with any of them. Should be good?
Yup, I'd say you're good as long as you looked closely. Here's what geology.com says about doing the acid test with vinegar.

"Vinegar can be used for the acid test: Vinegar can be a safe, economical and easy-to-obtain "acid" for identifying calcite and dolomite. Vinegar is dilute acetic acid that produces a very weak reaction with calcite and dolomite - best observed with a hand lens."



I personally have only ever used vinegar because I don't own any actual acid. I've never had it react but I normally just test rocks that I know have no carbonate minerals.

I'm almost positive that black rock is lava rock that got smoothed out by the ocean. Lava rock doesn't have carbonates so it's safe to use. That tan rock almost looks like dead coral though, which is calcium carbonate. If it is, it will increase the PH/KH in your tank. So I'd check that rock one more time and look under a magnifying glass or something.
 

Momgoose56

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ystrout said:
Yup, I'd say you're good as long as you looked closely. Here's what geology.com says about doing the acid test with vinegar.

"Vinegar can be used for the acid test: Vinegar can be a safe, economical and easy-to-obtain "acid" for identifying calcite and dolomite. Vinegar is dilute acetic acid that produces a very weak reaction with calcite and dolomite - best observed with a hand lens."



I personally have only ever used vinegar because I don't own any actual acid. I've never had it react but I normally just test rocks that I know have no carbonate minerals.

I'm almost positive that black rock is lava rock that got smoothed out by the ocean. Lava rock doesn't have carbonates so it's safe to use. That tan rock almost looks like dead coral though, which is calcium carbonate. If it is, it will increase the PH/KH in your tank. So I'd check that rock one more time and look under a magnifying glass or something.
One rock isn't going to change your pH that much, especially if your pH is already on the 7+ side. I've used rocks, dead coral, California clam shells, oyster shells and various other shells and driftwood I've picked up on beaches in the US and Mexico. I boil em and put them in. Never had a problem.
 

hanra85

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For the sake of a few drops of vinegar though, you'd have a clearer answer on how it's probably going to react to the water in your system. A large system might not make a difference but if they're going into a 5 or 10 gallon tank (even worse, if it were even smaller) I'd be willing to bet if that if it did in fact have the ability to buffer pH, it could potentially be by a fairly significant amount. I'm extra paranoid actually so soak any unknown rocks for a week or so in a bucket and re-test for any pH changes before I add them, I usually err on the side of unreasonable caution though. Lol.
 

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