Where to find Slate?

Hey guys--

I have an aquascape overhaul planned for my tank, and I'm wondering where I can find slate rock to use. Ideally I'd like to just go find it somewhere for free, but if there are places that sell it for a good price in Utah (small quantities), that would be great too.

Also, I understand shale is a different rock, but the look is similar, and I'm wondering if it's safe to add shale to my aquarium without worrying about raising my pH or otherwise harming my water parameters?

 

I can't answer the shale question, but a landscaping company/rock yard usually sells slate. At least in my area they do.

If you are desperate you can buy slate packs off of ebay. But that's expensive

 

I guess it makes more sense to piggyback my next question onto this topic instead of creating another one.

I found several great pieces of what looks very much like slate (although I suppose it could be shale) in the mountains nearby my apartment. Per usual, I did an acid test to check for carbonate/bicarbonate content, using the Nitrate Test #1 bottle from my API master test kit. All but 2 of the rocks I found fizzed.

My understanding is if you put rocks with carbonates/bicarbonates into the tank, they can potentially raise pH. My water is already very hard (GH is 200+ and KH is usually around 180). Consequently, my PH is relatively high, though I've tempered it a little bit with driftwood. PH usually sits around 8.0-8.1 in my tank, and my fish and plants seem to have adjusted accordingly.

I've avoided using any rocks that "failed" the acid test in the tank because I didn't want to swing my pH, especially towards an even more alkaline direction. However, my plans with these rocks are just to make sort of a "cobblestone path" as part of a new aquascape I have planned. It will run up a hill. I'm not adding any large pieces. I'll probably be adding between 10 and 20 small, roughly 2x2-inch, thin, flat pieces to form the path. This is a 55 gallon aquarium. I estimate I'll be adding less than 1 lb of rock.

Do I need to worry about this, or are my quantities small enough that the effect on my pH will be negligible?

 

I would suggest putting them in and monitoring your pH closely for a while. I've found some stones that failed the acid test didn't change my pH at all while some caused noticeable swings.

 

Okay. Aquascape is a little while off anyway, gotta wait for a paycheck.

I guess I could prepare the rocks by cleaning and boiling them, and then do a pH test by letting them sit in another container for a week or so and monitoring the pH there.

That would also be a good way to make sure I'm not getting into trouble by putting oil shale into my tank that's going to leach petroleum into my tank water

Thanks!

 

Another idea I think would be good is to do a bucket or tank of tap water and test the ph and then put the rocks in for a few days and then test again to see if it raises. That way if it raises there's no fish involved.

 

Yeah that's what I'm actually doing. I have a bucket of tap water sitting right now. After about 48 hours, I'll get a baseline pH, KH, GH reading. Then I'll scrub and boil the rocks and add them to the bucket, checking the pH, KH, GH again after maybe 48 more hours.

If it's gone up a little (like 0.1 pH points or less) I will use the rocks. If it's gone up more, or if I get oily residue (oil shale) I'll source them from elsewhere.

 

Okay, after sitting for a few days, the water straight out of the tap came in at

pH 8.0
GH 11 drops (~197 ppm)
KH 10.5 drops (~188 ppm)

I just scrubbed the rocks clean and dumped them in the bucket. I'll check back in 24 and again in 48 hours to see if the hardness or pH goes up significantly. I need to keep in mind I have more rocks than I'll use for the whole path in the new hardscape, and they're sitting in something like 1-2 gallons of water, not 55. So I'm thinking it's going to have to go up pretty significantly for me to veto these rocks.

Thanks for everyone's help!