Courious about rocks in a tank

[Manwithnofish]

I've found some rocks (size of a small football) full of small holes, lots and lots of tiny holes. Would these be ok to stick in my aquarium. I'm afraid algae will grow in the holes and I'd never be able to get rid of it. Any ideas on using porous rocks?

[Chrispy]

well get a nice large pan and boil it for a while. anything that was on it will die and it will me staralized. depending on the rock size i would boil it for about 5 mins. or if its large longer.

[shade2dope]

like texas holy rock-lace rock or...I dont have problem with it in the holes in my rocks but If I did I just use a new tooth brush to clean it.

[trashion]

hmm, i've heard bad things about porous rock and its capability to mess with the pH of your tank. pour some vinegar on it (or better, muriatic acid/HCl) and see if it fizzes. if it does, don't put it in.

[Manwithnofish]

Well I can't tell about any fizzin' because anything I pour on the rocks, instantly disappears (into the pours). Don't detect any fizzin' but won't swear that it ain't happening. Can't I just put the rocks in a bucket of my (well) water and see if the KH or GH changes ....you know a before and after test? If I'm doing frequent water changes (say monthly), any influence the rocks are going to pose would have to happen quickly to be a problem.

[Obsidian]

Monthly is not frequently and it is plenty of time for the changes to happen. And once the change happens you have to be willing to do smaller water changes more frequently because a larger one will cause Ph swings. I just learned this the hard way (I only used my high ph test and as a result did not know that my Ph had dropped significantly in my 10 gallon tank, the Ph swing set off disease in the tank after a large water change).

Even if the whole thing was holey there would be some fizzing at the surface that you would be able to see. If you can post a picture of the rock someone might be able to identify it and let you know if it is the kind that will mess with your water chemistry.

[Manwithnofish]

These rocks came out of a local mountain river. I pretty sure they are sandstone. My water is well water, so I don't see why my pH is going to change.

Let's just assume they do fizz. Is the problem that the rocks (those that fizz) increase the carbonates (hardness) or do they affect the pH or both. In either case, if I put the rocks in a 5 gal bucket of well water for a few weeks, I should be able to measure any changes by measuring before and after. If they don't affect the water within a month, it won't matter because the water gets changed that often anyway.

It just seems that taking actual measures for pH and KH / GH, would be better than trying to determine if the vinegar is fizzin way down in the tiny little pours that I can't possibly see. I'm not argueing about whether or not they would be bad. I'm just looking for a better test.