Flourish Excel doesn't have copper, regular Flourish does.
Still, a CO2 system is better than just Excel, especially at your light level.
The Hagen system is basically a pre-made DIY yeast system with a cool but bulky diffuser/bubble counter.
As for the other system using what looks like fizz tablets, I just don't see them lasting nearly as long as the yeast method.
Good to know thanks! Any reason I shouldn't use the Excel and CO2?