Will a sand substrate work for a planted tank?
Black Tahitian sand is what I have in all my planted tanks (and all my tanks have live plants). It’s a wonderful substrate, and if you have fish like corydoras, it’s the best substrate for their delicate mouths. You should not use an undergravel filter with plants, and with a sand substrate, it’s impossible to have an undergravel filter – the sand does not stay on top of it, and it becomes clogged. If you use a mesh covering, it becomes clogged. If you want plants and an undergravel filter, the only real way to go about it is to plant the plants in little urns and let them rest on the bottom of the tank and then use a medium gravel instead of sand as your base substrate. If you use gravel, an underwater filter, and have plants planted it it, sooner or later the roots get tangled up in the filter grid. Later, you’ll see them growing up the tubes in the corners. It’s a mess. If you want biological filtration with a planted tank, then you could use a basic air pump, air stone, and sponge
