When setting up a tank with plants, whether it will need some help cycling some bacteria or if it can pretty much handle fish due to the plant load, one thing is important, plant first and then do anything else.
There are several reasons for doing things this way;
1. Plants need time to root/establish;
a. The will often be uprooted by the fish in their normal activities if the plants have not had a chance to get a grip.
b. Plant roots change the composition of the substrate in terms of what bacteria is where and how the substrate functions. Planted tanks with roots in the substrate are totally different than tanks without these. This changes the cycling paradigm.
2. Plants consume ammonia (as NH4 and do so more rapidly than bacteria use NH3) so the more plants in a tank and the more nutrient demanding they are, the less need for bacteria there is. That means there is less need to cycle. Some tanks need 0 traditional cycling at all because of the amount and types of plants they have.
3. Some plants are more sensitive to ammonia and putting them though a normal fishless cycle may actually kill them. This is pertinent when cycling because ammonia levels are way way higher during cycling than they will ever be once a tank is cycled.
4. The level of ammonia used to cycle w/o plants and the time it takes to get a tank cycled for that is much greater than the time needed to get a tank with plants fish safe in terms of cycling issues. So, much of the fishless cycling efforts are a waste. They will actually be undone to some extent because the plants will take them over. This mean you will have spent time establishing an amount of bacteria that will die back when the plants are added. And the more plants that are involved, the more time and effort that will have been unnecessary.
5. Often plants do not need fertilizer initially as they come to us with a good supply of stored nutrients. So they get planted and then are allowed to settle in before fertilizing is needed. But if one is trying to keep bacteria doing well by adding ammonia, they are also fertilizing the plants which really do not need it yet and which could cause unwanted consequences.
Since you have already cycled your tank and now are planting, my advice is not to add any ammonia during the next two to three weeks while you let the plants establish. Once they have you can revisit the cycling issue by doing an ammonia addition to the tank of 2 ppm max. and then see how that goes. If in 24 hours it has vanished and you also get a 0 nitrite reading, the tank is for sure good to go. If you get a very low level reading of these things, you can still start to stock the tank but do so gradually instead of all in one go. I would want to see the tank process at least 1 ppm in 24 hours before adding fish gradually.
