Rocks.

[cinnastix911]

So i got some rocks from Topsy Reservoir near where I live. I scrubbed and soaked them in very hot water for awhile. I tested the pH and it was acidic/neutral (can't tell exact with my test kit) so I decided to see if this was just my water. I set out the rocks in water and then just a plain cup. It set for a few hours and I just checked it again. The cup was 8-ish but the bucket with the rocks was def. close to neutral. I checked the tap water fresh from the faucet and it was just a little less alkaline then the tap water that I had let sit.

So my question is...

The tests (that I have found) to see if a rock is aquarium safe only test to see if it makes the water more alkaline (muriatic acid and vinegar tests etc.) but what if it makes the water more acidic? Are the rocks safe?

 

[rich311k]

First off to be accurate you need to test your tap after sitting out for 24 hours before getting a true PH. The gases in water need to dissipate first. I would try it again. Fill a bucket let it sit for 24 hours test and than add the rocks just to be sure. I can not think of a rock that would lower PH.

 

[Stephen]

I don't think there are any rocks that make water acidic. I may be wrong, but I can't imagine what type of rock would have that property.

 

[cinnastix911]

That's what I found odd. The bucket was originally filled for alomst 28 hrs before I tested it. The second test was shorter but yielded the same results. I justnow tested again after reading rich's reply (same water as the previous test) and I got the same results.

And doesn't iron pyrite lower pH (I don't think I have any though lol)? There are some out there...