Aquarium Decor Altering Parameters?

[Yao]

I have a reddish rock in my 20 long. I'm not sure what it's called. I got it from a [acronym:2e906ec87d="Local Fish Store"]lfs[/acronym:2e906ec87d] and have had it in there since I set up the tank two months ago. It just dawned on me the other day that random things in the tank might raise the [acronym:2e906ec87d="power head or Measure of the concentration of hydrogen ions, depending on context"]ph[/acronym:2e906ec87d]. The rock I have is dark maroon/red, kind of brickish. One of those typical ones you see, odd shaped with a hole for the fish to swim through. Just wondering if anyone knows what this is called and if it alters my tank parameters. (I used a crappy test kit, and my [acronym:2e906ec87d="power head or Measure of the concentration of hydrogen ions, depending on context"]ph[/acronym:2e906ec87d] seemed high, not sure if it's just inaccurate, or if my [acronym:2e906ec87d="power head or Measure of the concentration of hydrogen ions, depending on context"]ph[/acronym:2e906ec87d] is too high)

While on that subject, I have a few petoskey stones in my tank as well. (Fossilized coral and state stone of michigan ) They are normal grey colored and you can see patterns when they're under water. I just started to notice lately that they are getting dark red rust looking spots on them. I'm sure these weren't there before. Does anyone know what could be causing this or what it is? I thought all algae was green, so I didn't think that was it. Does my tank have some sort of parasite in it or are the fish somehow doing something...?

[Fishyfanatic]

Is it Lava Rock? Does it look like the rock in this pic on the left side?



If so, it does not alter pH. Have you tested the pH out of the tap after it sits out for 24 hours? You could just have a high pH. Also, do you have any coral or sea shells in the tank? Perhaps limestone? If so, they will increase your pH.

[Dragonmommy]

OMG I added a bunch of rocks today including 1 limestone and hours later tested my [acronym:042b53ccd0="power head or Measure of the concentration of hydrogen ions, depending on context"]ph[/acronym:042b53ccd0] and it said 8.8!!!! I rested and it was fine seems I didnt clean my testing equipment enough.
You may wanna check and make sure you are using good clean testing equipment and if all else fails take a sample to the fish store and have it tested there.
As for the red spots, well I noticed those spots on some of the rocks I was browsing (outside dads house) and I avoided them because I was not sure either. I am figuring its some kind of mineral thing. If its not affecting your water much I say why mess with a good thing? You could always remove the rocks with spots during your next water change and see if your results differ over the following days.

Good luck!

[Yao]

Yes, it must be lava rock. it looks exactly like that.
The red spots weren't on my petoskey stones before. So I'm wondering what it is.

[Fishyfanatic]

Remove one of the rocks and put a few drops of vinegar on the rock. If it bubbles, it will increase your pH. If not, it's not affecting the pH.