Are these rocks ok for freshwater tank?

[beerad555]

I have just received these rocks as a Xmas gift for my tank as a surprise and i am leary about it. I have been told that you can test rocks w vinegar to make sure wether or not they are safe to put in tank, and if they fiz or bubble they are no good for tank. Just wondering if anyone is familiar w these rocks and if they are ok for tank.These rocks come from Kentucky creek beds. Here are some pics.

 

[bansheenoy]

those arent rocks those are miny bolders..lol

 

[beerad555]

yea they look big in pics , they are about 9 x 9 x 6 inches tall, and are going into 125 gal hopefully.

 

[sostoudt]

i may be completely wrong but they look like a type of quartz to me

 

[luohanfan]

i may be completely wrong but they look like a type of quartz to me

i agree.. look like quartz.. would be fine in a tank

 

[rasa92re]

That quartz. It's 100% aquarium safe as long as you don't accidently drop it in the 125 instead of placing it.

 

[Pufferpunk]

Only thing is, they are very hard--not porous, so not the best for biological filtration for a marine tank.

 

[limz_777]

looks like a cauliflower , another way of testing , is just putting the rocks in a pail with water and test your water parameters from there

 

[TwistedPenguin]

They're fine. The vineagar test only tells you if the rocks would make your water harder or not. And in most cases it wouldn't make a difference even if they did. Cool rocks!

 

[Pufferpunk]

I missed that you posted about these being for FW tanks, since this is in the SW section.