K is potassium lol so you're covered.
I have 2 low tech / med-high light tanks and dose with the EXACT same ingredients you describe.
Start out slow because if you over-do it algae will conquer you. I find that 1/2 EI works good for me with respect to dry ferts. Full EI dosing is too much for a tank that does not have CO2 injection. With low tech / excel you should not dose full EI.
EI dosing amounts can be found here.
Here is my schedule that has been working for a while:
Macro Day - 1/2 EI dose of KNO3 / KH2PO4 (these 2 should cover your macros)
Micro Day - Recommended dose on bottle of Flourish Comp (5mL / 60gal) / a bit of Trace as well (will cover micros)
Alternate macro and micro days so that dosing occurs every day.
Excel every day (important) - I do 2x the recommended amount personally. My fish don't seem to mind.
50% water change each week
Again, start slow because if your plants don't use it all up algae will...
Also another note - the recommended dose for Flourish Comp says to dose 5mL / 60gal each week. Don't worry about this - you need to do it every other day to give your plants what they need. The bottle does not take into account that you are dosing dry ferts as well...
How big is your tank / what lighting do you have? This will be a big piece in the puzzle