pH Down Calculator
Front Row Ag · pH Down Calculator
70% Phosphoric Acid · Alkalinity Neutralization
Water Parameters
Starting Alkalinity
ppm
Target Alkalinity
ppm
Batch Size
Volume of Water
gal
pH Down Dosing
Rate
0.69 mL/gal
Total for batch
0.69 mL
Neutralizing 100 ppm alkalinity (140 → 40 ppm)
Quick Reference
| Neutralize | mL / gal | mL / L |
|---|
How it works: Each ppm of alkalinity (as CaCO3) requires ~0.00694 mL/gal of 70% phosphoric acid to neutralize.
FRA recipes land in the 5.5–6.0 pH sweet spot with ~40 ppm residual alkalinity.
Always verify with a pH meter — dissolved minerals and CO2 can shift actual results.