[trenac]

KN03... potassium nitrate

With 4WPG are you injecting C02?

I dose Kent grow, Kent micros, Kent iron, KNO3 (Green light stump remover).

 

[trenac]

I would wait for 2-3 weeks before you start dosing ferts, if your plants have just been planted. DIY C02 is fine just make sure that you are injecting between 20-30ppm, you may have to use two DIY to get this reading depending on the size of your tank.

 

[trenac]

Three bottles should be plenty of C02, I run two bottles on my 55G tank.

I'm not falmilair with liquid Docin so I don't know what it contains. You do need to add micras/micros, iron and maybe some other ferts depending on what your tank is lacking. I use the kent line of ferts...
http://www.kentmarine.com/