The mopani I have in my ten gallon betta tank and my 55 goldfish tank have both been dremmel sanded so all the sharper parts are dull. Plus I attached lots of plants to the one in my 10 g betta tank to help too.
Yea, I filled it last night, I have yet to check on it cuz I didn't spend the night at home last night. I'll take pic to show the tannins.
I'm really hoping it turns out good!