I'm leaning towards a fluorite base with a topping of Onyx sand or Black
Tahitian Moon sand. When you have a sand topping like that, how do you
clean the substrate? Can you vacuum like you do with gravel? Or do you
just have to be sure you never over feed :-0. Does waste breakdown
better/faster in a planted tank?

Hi Tom,

I use 100% Fluorite so I cannot comment on maintenance of 2 layered
substrate. However a lot of people go without vacuuming planted tanks.
Plants use the waste as nutrients. My tank is very lightly stocked with fish
and I have about 30 Amano Shrimps that clean the bottom. It was established
2 years ago and now in more then a year it hasn't been vacuumed.

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Regards,
Marvin Hlavac
Toronto, Canada