Melting Aquarium Rocks

[Jaybird]

I bought what looked like, and was listed as, quartz from a LFS. Well, I don't think that what I bought was quartz.

Over three weeks, the rock has disintigrated into my aquarium water. I pulled out what was left and did a huge water change.

Has anyone else had rocks just disappear?

 

[Musket]

sorry, all I can think of is a sandstone or halite. But you probably would have noticed those.

 

[toddnbecka]

I tried keeping limestone crystal in a bowl of water once, to see if it wouls be suitable for aquarium use. It didn't fall apart that quickly, but did make a really heavy, solid film on the water surface after a few weeks. I've also noticed that marble tends to become slightly rough after being under water fir long periods of time.

 

[Jaybird]

This rock looked like a flat piece of quartz about 6" square but only 2" thick. Right now it is on my kitchen counter and it is only about 3.5" x 2" x 3/4".

I got a little paranoid about what that could be doing to my cichlids!

 

[JDogg]

most likely halite "rock salt"

mineral form of NaCl table salt

 

[toddnbecka]

Check your pH and hardness, they almost have to be much higher. Try keeping the rock in a bucket of water, and test the water a few times to see what/how quickly it changes.

 

[JDogg]

do you notice any bubbles coming off the rock when it is in the water?

what is your ph?

 

[Jaybird]

jdogg: That looks a lot like what I had!!

Man, and they sold it to me as quartz! I bet my water is well salted now. Crap!!

PH is at 7.2 right now. Normally it is around 6.8-7

Nobody told me I had to be a geologist to have an aquarium

 

[JDogg]

jdogg: That looks a lot like what I had!!

Man, and they sold it to me as quartz! I bet my water is well salted now. Crap!!

PH is at 7.2 right now. Normally it is around 6.8-7

Nobody told me I had to be a geologist to have an aquarium

as a geologist (well high school earth science teacher) i can tell you that ALOT of people can not tell quartz and halite apart. if you are brave the easiest and quickest way to tell in the future is lick it.

you can also look for cleavage. cleavage is when a mineral breaks along flat planes. halite has 3 planes of cleavage that are at 90 degrees to each other. quartz does not have cleavage.

 

[toddnbecka]

I'd at least demand a refund from the lfs. Actually, salt will break/chip much more easily then quartz.

 

[QTOFFER]

A few years ago, I remember seeing similar rocks being sold as "Utah ice" or Blue ice" or as some kind of quartz. They looked fantastic underwater, but they were salt crystals that dissolved and messed up the pH and hardness.

The easiest way to tell inorganic salts from quartz is to use the scratch test. A steel blade will scratch salt crystals, but not real quartz.

Nobody told me I had to be a geologist to have an aquarium

....or to run a lfs.
Bring what's left back to the lfs and get a refund. Maybe you can convince them to stop selling the stuff to other unsuspecting hobbyists too.

 

[Jaybird]

I'll bring up point the next time that I go there.

ATOFFER: you're right, it did look fantastic underwater, but it has raised my PH over time. I just thought that my water had stabilized. It comes out of the tap and even 7, but drops over time in the tank to between 6.5-6.8. It hasn't dropped for some time, and I thought it was because of the two limestone rocks I put in (I put them there to give my water some buffering capability so that they fish wouldn't be harmed from the ph change during PWCs).

At least the thing is out of my tank. Guess I'll have to be the freak at the lfs from now on......being the one licking all the rocks before taking them home