For a tank this size, I have a 350, I'd add 2x a week 1 table spoon of KNO3, more if you have a low fish load. I have 700w of MH, 8x55w PC and lots of CO2.
Dose 2x a week and when the plants fill in more, you'll wanna up that to 3x a week or add more fish.
1-1.5 TABLESPS KNO3
1 teaspoon KH2PO4
75mls of TMG/trace
GH, add about 1-2 degrees extra with SeaChem Eq of the GH booster from Greg Watson.
40-60% water change weekly, less as you get better and tweak it.