Petsmart has a bunch of nice stones and rocks, but they're pretty expensive. I really don't see anything special about their "betta rocks."
So, is it alright to use stones (smooth ones) from outside in a betta tank? If so, what is the best way to clean them to eliminate bacteria but keep them safe for the fish?
Do you have a dollar store? They have the same stones, and gems as well, at the dollar store for obviously less.
And yes you can use the stones from outside you just got to clean them good. Boiling them, and soaking them over night once the water runs clear is a good way of making sure they are clean and safe for fishes. Just be careful of sharp edges.
I have minnows which are burrowers (but more like dive bombers) so they defiantly test the sharpness of outdoor rocks.
I would not use stones outside for several reasons. One you don't know what the stone is made of and some stones do effect the water chemistry and it could be bad news. Also you don't know what kind of bacteria and other pathogens may be present and sterilizing them will be a concern. The only sure fire way to get anything out of them is pressure cooking.
I collect and use all kinds of things in my tanks that I gather outside around my house without problems-With that said, as long as these items haven't been contaminated or come in contact with harmful chemicals, pesticides...etc.....Generally they are safe to use.
I wouldn't boil rocks since some can explode or bake in the oven at high heat.
If the rocks are not porous-just give them a good scrub under warm running water. Be aware that some rocks can change the water chemistry over time as they leach.
If you pour vinegar on a rock, if it bubbles and foams, then it shouldn't go in your tank.
If it doesn't bubble, it's inert enough to go in the tank.
I've never done this, so I can't speak for its effectiveness.
Also, silicates in many "pretty" stones like quartz, amethyst, and also things like jaspers and agates can cause diatom algae growth as the silicates leach out. I am a rock hound who collects jaspers and agates, so I threw a few in one of my tanks, but have not noticed any algae, so maybe this isn't as real as I've heard.
Er, should have mentioned by boil I mean poor boiling water on them. I wouldn't necessarily put rocks in a pan on the stove directly. Yes they can explode, and think what they could do to the pan itself. But boiling really is just a precautionary step.
i go to my landscaping supply store. not the big box stores. you can save alot of money and put your self at ease knowing that they are already sorted and identified. for example. i wanted petrified wood for my aquascape, i costs 3$ a pound at lfs. at my landscaping store it costs 1$ a pound. keep in mind that they will change ph. put them in their own glass of pretested water and test again 2-3 times in a week. this will let you know how much the stone will change ph. jade , texas holey rock, petrified wood, granite, slate are all safe. pagoda stone and dragon stone are also safe but harder to find. marble and sand stone are not good. the test that bethymt described above (vinegar) is also helpful. i scrub my rocks in hot water and put them in a bucket of bleach water. rinse repeatedly and let soak in a bucket with water and double dose prime or other chlorine remover.