I'm new to this and I'm trying a middle road approach to this, and I'm not sure which way to go as far as fertilizer goes. The only thing that I have been using so far is Flourish Comprehensive and what is in my substrate. The tank is pretty new and I have been having considerable growth as it is, without algae. It is 2.1 watts/gallon with CO2. The plants have been growing well except one that totally melted and is now regrowing and some blackening on the tips of the leaves on a lace java fern. The leaves on some of the plants may be paler than they were when I got them (particularly an anubias). I don't really have a frame of reference to know what the plants should look like healthy. I have some swords, hygro, and water sprite that are growing at a phenomenal rate. I'm new to this and I'm trying a middle road approach to this, and I'm not sure which way to go as far as fertilizer goes.
TANK SET-UP AND HISTORY:
Tank has been set-up for about a month, but started with cycled media, substrate, etc), but then 2 weeks ago I added some Aquasoil Amazonia and the cycle was broken and the pH dropped to insanely low values < 6.0 (below the bottom of the range measured by API kit). I have been doing a lot of water changes to save my fish, although I lost a few catfish) but I am nearly cycled. I still have some ammonia but I also have NO2 & NO3. I am upset that there was no warning on the aquasoil that this would happen, I would not have put it in my tank.
Using and Flourish Comprehensive
15g tall (20x10x20in) tank
Eclipse 1 Hood
Replaced carbon filter cartridge with filter pad and Purigen
32w CF lighting (retrofit from the stock 15w) on 12hr/day
Redsea Turbo CO2 Bio-System (just installed)
Substrate (50% Flourite, 35% Amazonia, 15% large black gravel)
Fish: 6 female betta, 5 pygmy cories, 2 otos, and a juvenile BN Pleco.
Tap GH=10, KH=8, pH=8.0, no N compounds
Tank GH=11, KH<1, pH<6.0 (until I used baking soda to raise KH)
last test before WC Ammonia=0, NO2=0, NO3=10