My first saltwater tank was set up in high school and it was a 10 gallon FOWLR tank. I definitely made a lot of mistakes with it, 1 was using tap water to mix the salt, 2 was the second fish that I put in was a Mandarin Goby 
(thankfully my neighbor had a 200 gallon reef tank and he took him in for me), and 3 was the only filter I was using was a small HOB filter that was definitely not providing enough movement or filtration. Needless to say that Tank only lasted about two months before I took it down and rehomed the inhabitants. If I could go back I would definitely start with a larger tank, do more research on the fish I wanted to add in, and get adequate filtration and supplies to take care of it. If you were able to redo your first tank how would you do it differently?
(thankfully my neighbor had a 200 gallon reef tank and he took him in for me), and 3 was the only filter I was using was a small HOB filter that was definitely not providing enough movement or filtration. Needless to say that Tank only lasted about two months before I took it down and rehomed the inhabitants. If I could go back I would definitely start with a larger tank, do more research on the fish I wanted to add in, and get adequate filtration and supplies to take care of it. If you were able to redo your first tank how would you do it differently?
