I wanna preface this by saying I have a 39 gallon that's been set up for almost a year now and have had absolutely zero problems with it. This 5 gallon tank! Idk what I'm doing wrong I've had 2 bettas and now my African dwarf frog die in this tank. I change and treat the water once a week, the same thing I do for the 39 gallon, and to no avail fish keep dying. I'm thinking of changing to fluval substrate for the plants because they are just not growing (or dying) in this sand. Do you think that could help my problem? The water must be getting toxic before I change the water maybe because it's such a small amount of water? Lmk what you guys think because something needs to change before I even think about putting something else in here.