What djlen is suggesting is sometimes called a silent cycle. Plants use ammonia and nitrate as a source of food, just like the bacteria in the cycling process. If you load up with enough fast growing plants in the tank (won't take much for a 5g tank) the plants will absorb all of the ammonia before it can become toxic to the fishes. Some good plants for the job are hornwort, water wisteria, water sprite, and anacharis. You don't need to keep them if they don't appeal to you, just keep them in there long enough for your primary plants to establish themselves. Plant heavily, say 10 stems of whatever bunch plant you choose in addition to your primary plants. The old mulm is extra insurance that the bacterias for the cycle process are present should the plants not absorb all of the ammonia.
Flourish Excel is sufficient for small tanks but a constant and stable source of CO2 is better, so if you already have pressurized CO2 handy use it.
Flourish Excel is sufficient for small tanks but a constant and stable source of CO2 is better, so if you already have pressurized CO2 handy use it.