Originally Posted by HD Blazingwolf
So basically a hob full of cotton balls, or some cottony material would be best suited to absorb the dye. No?
Cotton pillow batting?
I'm not sure if it's really fair to call it a dye, or if removing it would serve any purpose.
CSM+B contains 2% manganese, a necessary nutrient. It's probably EDTA chelated in that source, so I don't know if plants can directly or efficiently utilize what the substrate is releasing.
Manganese is toxic if overdosed, the Wikipedia article and MSDS for manganese dioxide are rather scary to read. That's the reason I never pursued dyeing substrate at home on any useful scale, only a few small test batches to satisfy my own curiosity.
It's certainly eye-raising to see enough manganese in a tank to be detected with a mere paper towel.
But I'm not going to panic, or suggest anyone else do so either. If this was a significant issue, I'd imagine we'd have noticed a few "Flourite Black killed my fish" threads by now, right?