What bulb are you using, what is the Kelvin temperature of the bulb, wattage? Any tank is capable to have CO2 and it benefits greatly from CO2. If you use CO2 you actually get away with a less powerful light. Baby tears should have sand or some type of aqua soil that will prevent rooting, so flourite or aquasoil is best, gravel isn't very good for it.
I am not saying it is fool proof as it is a demanding plant, but it is worth a shot.
15 Gallon NPT
1g no tech bowl in the making