Is this rock safe for my tank?

I have attained some rock to build caves for my 55. Only problem is, I do not know if it is safe. Any ideas?

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Generally if you see flecks of minerals they say not to use it. Also if you pour vinegar on it and it fizzes they say not to use it. Those are the general guidelines Ive heard on rocks.

I don't see flecks. But the red may be iron. Not sure.
It did pass the vinegar test though.

Peylix wrote:I don't see flecks. But the red may be iron. Not sure.
It did pass the vinegar test though.

Yes, that rock looks as if it has a high iron content. I would not use it.

Iron, the commonest of all metals, is normally present in nature in the form if iron oxide, i.e. rust. It follows that if you have rocks containing iron, betrayed by rusty streaks and patches, it will not normally present a chemical problem for your fish since the rust, iron oxide, is inert, However, if there is enough rusty material it will discolor your water, so rocks that are heavily 'rusted' should not be used. A few patches or spots of rust here and there on rocks is not a problem.

If you consider that the rotor of every pump motor in your tank is a cylinder of pure ferrite (magnetic iron powder sintered with strontium, barium, etc.) rotating at high speed on a steel spindle in constant contact with the water and at a temperature above the tank ambient (i.e. perfect conditions for chemical reactions) you can see that there is little need to worry about a few rust stains on rocks.

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Just read that article a while ago haha. Question. If it is high in concentration to where it would hue your tank water. Would boiling it be a good test? See if it hues the water in the pot first?

IDK if that would work. I have used many natural rocks all I can say is if it was red, felt chalky, could scrape dust off with a metal scribe (or something) I wouldn't use it. If the surface was super hard like granite then I would probably soak it for a while and see if it begins to deteriorate/erode. This would collect at the bottom of whatever you soaked it in, and if it was red would be iron. I wouldn't use it.

If this rock was super hard, passed the soak test, dried it off, didn't get rust film on my hands or towel then I may contemplate using it.

I've used rocks high in iron. Too high of iron will disrupt parameters in the tank. This could effect fish health, cause excess algae, or just make the tank funky by coating the whole tank in a dusty red color.

I would post it to reddit.com/r/rockhounds and see if they can identify it.

I had a thought and perphaps it would not work... but put the rock in a 5gal white bucket or maybe a spare 10gal tank. Put a powerhead blasting it. Wait 72hrs. I would guess that the constant pressure would release any iron oxides into the water. Rocks are so tough to judge. I have a "ring" of pumice that has calcium deposits but my PH and hardness remain low so its tough to say what will bleed into the water and what wont.

I dont believe the iron will hurt the plant per say. Might even be a bonus to plants but the discoloration would really suck. Let us know what you decide, and if you use it if you notice any effects.

I have used before and still currently have many wonderful rocks i have collected all over washington in my tanks. I usually soak them in a bucket for a few weeks, then boil them, and then place them in a tank with a couple of fish i am not very attached to. I know this sounds elementary, but if my fish show no negative side affects, then I move them into my display tanks. The vinegar test sounds like a great idea in this case!

I used some rocks that looked very similar to that before I noticed that after being in the tank for awhile they developed a rust type coating in some areas,so I took them out. The funny thing is I got those two rocks from a fish store. But I have used rocks I got by the ocean, rivers, yards, I just boil them for 20 mins. The rule I use is looking 4 specks that look like metal/minerals, and I throw em on the sidewalk because from what I heard hard rocks are good and softer rocks that break easy are the ones to watch out for. I'm not gem certified though! I just looked at you rock again and I'm going with FishNABowl I would pass on that rock I think you will get the rust stuff over time.

Thanks for all the input. The rock pictured is 1 of 6 that I have. I did however boil it for 8 hours and then tried to scrape off parts. The water used to boil did not tint nor were there any pieces that boiled off. Scraping provided no flakes and everything seems well.

Currently that rock is in my 55g and I've been testing the water 2x daily to see if any fluctuations occur. Nothing yet. So for now I'm gonna call it safe and finish my rock cave.

Again thanks for all the input. It's greatly appreciated.

 

You have to be a special sort of person to get into the aquarium hobby.. I mean who else in their right mind would be in the kitchen boiling ROCKS. Think about it...

You damn rock boilers!!!!!!!!!!!!!!!!!!!!!!!!

My roommates freaked out when they saw me boiling some big rocks and pvc pipes... Rock Stew with plastic noodles they called it.

Glad your rock is doing good Peylix. Don't forget to share the result!

Pro rockhounder here. Yes, 100% safe. That's a nice hunk of Jasper aka agate, made from metamorphosed silicates. BTW, if collected locally I'd love to know location...

DMD123 wrote:....Also if you pour vinegar on it and it fizzes they say not to use it....

A word about testing with vinegar (or pouring any other acidic liquid on the rock). If it fizzes, it's a reaction with CaCo3, which is basically limestone. That's what you would be testing for.

There is nothing wrong with using limestone type rocks in your aquaria, IF YOU REALIZE IT MAY HARDEN YOUR WATER COLUMN! I've used hundreds of pounds of limestone in some of my tanks. Fish like the African Rift Lakes Cichlids do nicely with limestone rock and calcium based substrate. There are others that do fine as well. It's all about what conditions you're trying to establish in the tank.

I bet you're gonna like the way your caves look when you're through building them.