Just to add to some of the other posts in reply here:
I had been doing evaporative top-offs only for 6 or 7 months and no fertilization regimen. I'm out in the country on a well and was concerned about what was in the water (for no real reason) so went with RO and I'd hoped my fish stock and a deep substrate would provide plant nutrition. I watched my plants slowly die back and new plants would melt within a week. Needed to change something so I turned to Easy-Green, Easy-Iron and Flourish. As it happened I also came into a CO2 rig freebie and got that going too. Also returned to well water and a once-a-month 30% water change since it had always been fine.
It's been two months now and things have really turned around and plants are doing well (as is the BBA, but I'm dealing with that).
I view Easy-Green and Flourish as complementary since the former advertises as a macronutrient supplement and the latter as a micronutrient so in my mind (and tank) they go together. Easy-Iron because the water consistently shows low iron when tested.
I shopped around for CO2 refills and have gone to a local welding supply for it. I'm getting "food grade" CO2 at US$39.00 for 10 lbs. I tried a local beverage center and they wanted literally twice that.
I agree with what's been said about Excel, it seems better as a fairly safe algacide than a CO2 replacement (which is what I'd thought before I dug into the what it's main ingrddient is).