Known safe lava rock?

[Fishkeeper]

Where have y'all bought your nice-sized (fist size or so) black lava rock that turned out to be safe? I need a bunch for a 30gal tank I'm setting up. If you look on any planted tank forum, everyone will tell you that the rocks aren't safe to use because they might have contaminants. Everywhere that sells lava rock just for aquariums tends to be super expensive.

I know you should soak the rock in distilled water for a few days before using.

What rocks have y'all bought and used long-term (at least a year) that have worked out? I'm specifically hoping for brands, if possible.

[Oople]

I’ve been looking for the same thing but didn’t find it. I wanted to glue a bunch together to make a focal piece for my new tank. I ended up just getting a single big chunk at Petco. This was the only place I found black lava rock bigger than gravel. I’ve read that people have gotten it at Home Depot/Lowe’s for use in fire pits but I couldn’t find any near me. There was some on Amazon but that will depend on whether they ship to your area. Good luck!

[Ula Hula]

I got a couple of big lava rocks at an aquatic pet store called World of Wet Pets. If you have a tropical fish store near you that's your best bet.

If you do find some rock that you're unsure of, I would imagine you could boil it in distilled water for several minutes to kill any critters lurking in it.

[Fishkeeper]

It's not critters I'm worried about, it's chemical or other material contaminants. Those are a lot harder to get rid of than critters. I'd imagine critters would die from the salty water, anyway.

[Decat]

I looked up a few lava rocks online and I finally called American Fire Glass and asked if any of there lava rocks were treated with chemicals of any kind. I was told by a rep that they DO NOT contain any chemicals of any sort and are straight from the lava fields and would be safe for aquariums. I am setting up my first tank and I am going to go on her word and order a bag of large rocks. i will still rinse them very well before putting them in the tank. But I am just starting so haven't even started to cycle my new 5 gallon. Just thought I'd share.