# Question about making rocks safe for aquarium



## matt1321

I recently bought some Flagstone rock from a garden supply store -- My question is how do I make it safe for the aquarium? I believe I am supposed to boil it. But for how long? And do I need to use any bleach ? Any help would be appreciated.


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## kmuda

"Boiling" is generally used whenever you need to treat something that was previously submerged in water, to kill off any parasites or disease the rock (or wood) may be harboring. Considering the rock is from a garden supply store and has never been submerged (at least not anytime in the recent past) it is likely unncecessary to boil it, although it would still be recommended. Boiling for about 30 minutes should eliminate any concerns.

Whenever I boil something, I usually also salt the heck out of it (Dead Sea Strength on the salt) and the salt in the water also causes it to boil faster.

Bleach is not necessary. Not in this case. Especially if boiling and salting.


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## matt1321

Ok so the boiling in water is to kill the bacteria and parasites What is dead sea strength salt? -- Is there anything to do to see if the rock is safe for aquarium use? Is Flagstone typically safe ? And if not how would i know? Or how can I make it safe? Is there a way to know if there are unsafe chemicals or minerals on the rock?


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## jrf

You might want to take a look at this article for some general guidlines: Suitability of Rocks in the Aquarium
A Practical Guide


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## kmuda

Dead Sea strength is officially defined as "a whole lot of salt". :lol:

Flagstone is compressed sandstone, so should be inert and not a problem.

The best way to test rock is to fill up a bucket with distilled water, test the pH, drop in the stone (or stones), along with an aerator, let it sit for a week, then test the pH. If the pH increases (very possible with some types of rock) or decreases (less common, but possible), then you should reconsider using that rock, unless the change in pH is something you are actually looking for. It would be best if you could test for pH, KH, and GH. While it is unlikely a rock can increase KH without increasing pH, it can increase GH (General Hardness) without increasing pH, so it is possible just a pH test could miss something. Something in your tank that is increasing general hardness potentially can cause problems with your fish's ability to maintain body fluid levels and is something to be avoided. Of course, with Africans, this may be something you are trying to achieve but with South Americans it's a big no-no.

There are other tests, such as scratching the surface of the stone (preferably an area that will not be seen) and pouring an acid on it. If it bubbles up, the stone contains elements that will increase water hardness. The best acid for this use is muriatic acid. So if you happen to have been cleaning some concrete recently and have some muriatic acid laying around, it can be used to determine if the rocks will increase pH, KH, and/or GH. Something many of us have in our toolkits is an API Nitrate test kit. Bottle 2 contains 41% Hydrochloric Acid and this can be used in the same fashion.


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## Toby_H

Unrelated to the OP's question but on topic for the title of the thread...

Quartz rock often contains arsenic... often in quantities that can cause issues in a fish tank...

I found a bunch of quartz on a construction site and mentioned it to one of our geologists. He mentioned the arsenic so I let him test one of the rocks. He broke up a piece and soaked it in something... tested the solution and said it had over 100x the acceptable quantity of arsenic for drinking water... in his opinion it was enough to dissolve in water to be deadly to fish, I didn't test his opinion...


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## newbiejess

hi guys....

what about rocks from the garden....

i have a convict cichlid tank and im jus wondering if it would be safe to use any rocks or should i really be only buying the from fish store??

thanks


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## DJRansome

You cannot make a rock safe unless all it needs is cleaning. Avoid rocks that might have been exposed to harmful chemicalcs like fertilizers or pesticides (like public garden or lawn areas), especially if the rock is porous...impossible to remove. Avoid rocks containing metal.

I use rocks from my property, but it is wooded and natural.

Your flagstone is likely slate. I would soak it in warm water, scrub it with a wire brush and run it through the dishwasher on sanitize with no soap or rinse agents. Note I have been warned that pieces can break off and ruin your dishwasher motor, so be forewarned.


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## newbiejess

thats great, thanks heaps for the info


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## Dj823cichild

Wow 2 posts back to back that I really needed. I just picked up some rocks from my local hardware store and I will follow the advice given. Thanks guys you just made my day a lot easier! Happy New Year my Cichlid Forum Friends! :dancing: :dancing:


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## TKC747

DJRansome said:


> You cannot make a rock safe unless all it needs is cleaning. Avoid rocks that might have been exposed to harmful chemicalcs like fertilizers or pesticides (like public garden or lawn areas),


DJRansome, what if you used bleach ( a base) then vinegar (an acid)? What exactly is in the fertilizers that makes it unsafe for aquarium use?


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## Dook

also, take note, boiling in water that contains bleach is a VERY bad idea unless you are doing it outside using a fire and large container of some kind. This process will give off deadly vapors. Not a good idea.


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## DJRansome

The pesticide or herbicide might have permeated the rock if it is porous. But when I said you can't make a rock safe, I meant if the rock itself was poisonous, like copper ore or something.

The acids and bleaches will clean a rock, but it could still be unsafe.


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## PfunMo

Sometimes there seems to be a bit of overreaction about bleach. If hot water and bleach were deadly your mother would have been dead before you were born. Before the days of water heaters, water for laundry was boiled on the stove and lots of bleach was used with nobody dying on laundry day. Reading the label on bleach will tell you that it comes with the chlorine very diluted. It does not come with a warning not to heat it. Boiling water hurts more people than bleach. I find it handy for telling me if there are any iron deposits in rocks. Since chlorine reacts quickly with iron it will produce a rust spot if there is iron in the rock. I ditch those as potential trouble.


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## Rhinox

Toby_H said:


> Unrelated to the OP's question but on topic for the title of the thread...
> 
> Quartz rock often contains arsenic... often in quantities that can cause issues in a fish tank...
> 
> I found a bunch of quartz on a construction site and mentioned it to one of our geologists. He mentioned the arsenic so I let him test one of the rocks. He broke up a piece and soaked it in something... tested the solution and said it had over 100x the acceptable quantity of arsenic for drinking water... in his opinion it was enough to dissolve in water to be deadly to fish, I didn't test his opinion...


Interesting. What do you think about the quartz sand, such as colorquartz or spectraquartz?


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## Toby_H

Rhinox said:


> Toby_H said:
> 
> 
> 
> Unrelated to the OP's question but on topic for the title of the thread...
> 
> Quartz rock often contains arsenic... often in quantities that can cause issues in a fish tank...
> 
> I found a bunch of quartz on a construction site and mentioned it to one of our geologists. He mentioned the arsenic so I let him test one of the rocks. He broke up a piece and soaked it in something... tested the solution and said it had over 100x the acceptable quantity of arsenic for drinking water... in his opinion it was enough to dissolve in water to be deadly to fish, I didn't test his opinion...
> 
> 
> 
> Interesting. What do you think about the quartz sand, such as colorquartz or spectraquartz?
Click to expand...

I work for an Engineering Firm and coincidently got that advice from our resident Geologist while showing off my new rocks at the back bay...

Based on the explanation he gave me at the time...

Quartz formed in layers as liquid sediment solidified... the components that create arsenic form under similar conditions as the components that form quartz... and they solidify under similar conditions as well...

Thus there are likely to be arsenic layers within the layers of quartz...

My guess would be that in when quartz is broken down into sand, any arsenic that was tapped between layers of quartz is released... and able to be washed away...

I would not suggest that quartz sand is at risk of causing arsenic poisoningÃ¢â‚¬Â¦ although I would wash it thoroughlyÃ¢â‚¬Â¦


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