Hello I am worried about your coral sand. You do not need a lot to have an important modification of your water parameters, you would be better without it.
What is the purpose of using the coral sand anyway, it makes no sense to me.
Angelfish, tetras, like soft water. Goldfishes are for external basin, they have no place with angelfishes and tetras, they will likely stress the angels, and when they get big (a goldfish can really grow big 1 even 2 feet), they could eat the tetras.
Newbie with plants, Quebec.