Found some rocks in my garden (had to dig them up) What are they? Is it safe for my tank?

Hi guys

So im doing a complete tear down of one of my tanks , and decided to remove the driftwood from there for another tank and sort of go with a rock theme, Been finding it extremity difficult to find rocks .

But stumbled upon these while doing some digging and gardening in our garden . Im not sure where they were from but they were deep in the sand.

I power washed them with the Karcher to remove the dirt and sand . Haven't scrubbed them down , boiled them or anything yet.

I have tested them with a very strong acid and there were no bubbles overall , (I used hydrochloric acid)
One rock had a tinly line along one side that did bubble , and one or two spots on it that bubbled but very tiny .

But im still unsure if they are safe to use for my tank , I plan on using this with tropical and maybe discus fish .

Can anyone identify what rock this is? Im in Durban Westville . I really want to use them . But have to be sure they are safe for my fish .

 

Just for reference , The thin line that i mentioned that bubbled can be seen on the two larger rocks , its those thin white lines at the top . and the tiny white spots are those that bubbled (not all though just one or two) I don't know if they go deep or possibly just cracks .
I also did ask about dolomite rocks on the forum some time back but never ended up doing anything with them , to many mixed opinions from here and the local pet shops so I gave those a miss.

But now that I found these in my garden (we don't use pesticides or any chemicals in the garden ) im hoping these should be ok? But have no idea what they are.

 

@Zippy320 ,


Sorry..not sure what rock that is, however we usually do the vinegar test and rule of thumb, if no bubbling its ok
Im not sure if the hydrochloric acid can also be used.. Maybe @TheGrissom or someone with better chemistry knowledge can shed some light there

What I would like to say though is, please.. dont boil rocks, its dangerous as they can explode
I usually scrub with salt and then rinse off

 

@MariaS Thank you so much for your quick reply , I really appreciate it .
I tried vinegar , used the cheap ones , the expensive ones but no bubble , so Thought let me use a really powerful acid to check for bubbling

Yup , Have heard that they could explode , I planned on filling a bucket with hot water (maybe adding some boiled water from the kettle) , its not really that hot , I don't think the hot water from our tap is that hot as it wont burn me when touched , add some salt to the water and let the rocks sit in there overnight . By that time the waters should be cool . I would then scrub the with a wire brush to remove the green thats on the rock . Let me see If I can get a clear closer picture of the rocks .

 

Thats perfect, pouring boiling water and salt is fine
We have had people actually boiling them in a pot, thats when its dangerous

 

Hi Zippy,

Yes any acid will work. the bubbles are carbon dioxide being released when an acid and a carbonate react. No bubbles means no carbonate which means the rock wont dissolve in the water. These rocks should be safe. While on this topic if you do the usual water change routine of 30 % weekly you will be removing any carbonates out of the water at a faster rate than they dissolve anyway.

 

What will lichen do in a tank?

 

Rot and cause an ammonia spike.

 

I'm just guessing here but probably it will foul the water as it is a living organism which will die submerged..
Stand to be corrected.

 

Was also thinking it should, then a good scrub and soak in a bit of water with Safe or Prime

 

Thanks So much guys , I really really appreciate all the assistance , Im just so happy to find these rocks ,Been searching for decent rocks for ages .

Here are close up of the rocks , I had no Idea about the lichen , Will bleach kill it off? I did plan on scrubbing it with a wire brush as well .

I wonder what type of rock this is? can it leach anything else in the water? The thin like you see in the first image up close that's what bubbled .

 

So lets see , I filled two buckets with hot water , added thin bleach and a little vinegar to the water , added the rocks , now I will leave them to soak till maybe tomorrow afternoon (when I get back from work) or possibly Saterday . I did find one oddball of a rock as well , its kind of glittery , and of a much lighter brown color , I wasn't going to use it , It didn't bubble either when I did the acid test , but once I added that to the water it seems to be bubbling a lot so its probable very porous . I'm definitely not using that stone but it helped increase the water height over one of my large stones. So I just left it in there. Once I take them out , I will Pressure wash the stones again , Scrub them , Pressure wash them again , let them soak in clean water and then use them , Am I following the correct procedure?

 

Sounds good. Perhaps a bit of overkill but rather safe than sorry. Use unscented bleach. Bleach will decompose in water to water and chlorine. Then you can either use safe of expose it to air for the chlorine to dissapate.