I hate Malaysian Trumpet Snails - I don't care if they aerate the gravel... as far as I'm concerned, the gravel is fine the way it is. They will absolutely explode in the tank and the gravel will become a floor of snails. But that's just my 2 cents, maybe others have had better experiences with them (mine were introduced on accident through a fish or plant so I never wanted them in the first place).
As far as your setup, I like it but the heater is in too prominent of a place... I say put it vertical on the left side of the tank to hide it away and you don't need that thermometer on at all times so that can go too.
I also don't know much ab out black petco sand but I assume it has no nutrients like eco-complete, flourite, or ada aqua soil. From my experiences the substrate is really important and though initial costs might be high (not really for a 10g), it's well worth it in the long run. Aqua soil in particular helps buffer the water to make it suitable for fauna and has nutrients in it for the plants, so win-win. Depending your tap water, the PH in your tank might be pretty high because of the slabs of rocks in there and no other PH buffering things (like peet which is in aqua soil).
But hey that's just me, people can make great tanks with that substrate it's just I don't see benefits of it (aside from the looks) whereas there are substrates now that I mentioned that really do help the plants grow.