What black substrate is geopahgus and corydora safe?

Really helpful, thank you! I ordered the estees black sand off Amazon, I’ll let you know how it is.

I know this is late and you may have already found something, but I experienced a lot of floating with the imagitarium sand. My favorite black substrate is the caribsea black sand, which worked well when I had Bolivian rams who did quite a bit of sand sifting. I have no experience with blasting sand.

The website indicates it is the plastic coated substrate is sold for all types of aquariums and fish. The coating makes it smooth so the substrate will not abrade any fish which dig or push through the substrate or suck it in and out of their mouth.

The only case I think the plastic coated substrate would not work is when you want the substrate to maintain a high pH as in Rift Lake tanks.

Is it safe for sand filtering fish ?

I remember when you could buy plastic coated gravel of any color. You still can.

Check out this link: http://www.naturesocean.com/Aqua-Terra.pdf

That sounds reasonable

I've always been skeptical about using black diamond blasting sand. I worry that it is too sharp and will harm the barbells of the fish. For that reason, I've never tried it.

Thank you! The internet mentions black diamond blasting sand as safe but I am not sure. Also imagitarium sells an inert black sand, but again I didn't know if anyone had any expereince with this.

Great question! I've looked for such a thing before, but it's not easy to find. I had some Estes black sand that I used in a 10 gallon aquarium for a while and it was fine for Corydoras. It's not cheap, however. I don't know if this version of Estes is small enough for Corydoras are not:

https://www.amazon.com/Estes-Black-Aquatic-Sand-25Lbs/dp/B07RR9JBDX/ref=sr_1_4?dchild=1&keywords=estes+aquarium+sand&qid=1613228692&sr=8-4