Typical PO4 sources are tap water (test that), fish food (rotting or processed by the fish), decaying plant, algae, other life in a tank and fertilizer dosing. Make sure that you clean up any detritus and clean your filter. There are phosphate reducing media for filters, but you should be able to control it without resorting to that.
One problem that I see, is your zero nitrates. In a planted tank, nitrates should never be zero. Wth pressurized CO2 and zero nitrate levels (if you are sure about those readings), your plants will stall and may die. So, they are probably not taking up any of the phosphate if they are starved for nitrogen or anything else.
Since you are injecting CO2, you don't need the Excel, although it won't hurt.
If you want to discuss your overall setup,please provide as much of the following as possible:
- Light (make & model): ideally, PAR and PUR reading at the substrate and photoperiod?
- What is the CO2 ppm level and how is it measured??
- Current pH and TDS readings?
- What you are dosing (product and quantity) and how often?
- Substrate type and how long has it been in place?
- What is your filter setup?
- Cleaning regimen (filter and water change frequency and amount)?
- Circulation: surface rippling and are all plants gently moving from top to bottom?
- What is your water source and do you use a water softener?