FinsFlora

PPS-Pro dosing

PPS-Pro doses a small amount every day, aiming to replace roughly what plants use rather than flood the tank. Levels stay low and steady, water changes can be smaller, and it suits lower-light or lower-CO2 tanks. The trade-off: it's lean on purpose, so you watch the plants and adjust. You mix two stock bottles once; this tells you what goes in them and how many mL to dose each day.

Water & bottles

Leave the daily dose blank for the PPS-Pro standard: 1 mL per 10 US gal. Pick a round number that suits your pump or syringe.

Target per day (ppm = mg/L)

Defaults are what the standard PPS-Pro recipe delivers.1

Mix

Into the bottleGramsg / 100 mL

Dissolve in about three-quarters of the water, then top up to the bottle size. Grams are per bottle, not per dose.

Dose

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Where levels top out

If plants took up nothing, a weekly change of 30% holds each nutrient below this ceiling.3 PPS-Pro assumes plants use most of it, so real levels should sit far lower.

ppmPer dayPer weekCeiling (before WC)After WC

For comparison, the EI defaults on this site add 22.5 NO3, 3.9 PO4 and 0.30 Fe ppm per week.

How this is calculated 
Standard recipe (reference only; targets are editable):
  Macro bottle: 500 mL + 58 g KNO3 + 4 g KH2PO4 + 33 g MgSO4·7H2O
  Micro bottle: 500 mL + 8 g CSM+B
  Dose: 1 mL of each per 10 US gal (37.854 L) per day

Daily ppm the recipe delivers = g/500 mL × 1000 mg/g × 1 mL ÷ 37.854 L × fraction
  NO3  58 g × 0.61328 → 1.879     PO4 4 g × 0.69788 → 0.147
  Mg   33 g × 0.09861 → 0.172     Fe  8 g × 0.0653  → 0.0276
  K    58 × 0.38672 + 4 × 0.28731 → 1.246

Your bottle, for any target:
  doses per bottle = bottle mL ÷ dose mL
  g in bottle = target ppm × V ÷ (fraction × 1000) × doses per bottle

Mass fractions: KNO3 NO3 0.61328 · KH2PO4 PO4 0.69788 · K2SO4 K 0.44875
                MgSO4·7H2O (246.466 g/mol) Mg 0.09861

Ceiling with no uptake: D = 7 × daily ppm, f = weekly change fraction
  before WC = D/f;  after WC = D(1 − f)/f

Notes

  1. Recipe provenance. 58 g KNO3, 4 g KH2PO4 and 33 g MgSO4·7H2O per 500 mL, plus 8 g CSM+B per 500 mL, dosed at 1 mL per 10 US gal, is the PPS-Pro recipe as it is widely circulated. We haven't been able to check it against the original author's page. If your source differs, type its daily ppm into the targets; everything else follows.
  2. Solubility. Limits used are single-salt figures at 20 °C (g per 100 mL water): KNO3 31.6, KH2PO4 22.6, K2SO4 11.1, MgSO4·7H2O 71. Several potassium salts in one bottle hold less than each would alone, so we warn at 60% of any limit. Cold storage lowers it further.
  3. The ceiling ignores plant uptake, so it's the most that can build up, not a prediction. It assumes one water change of the same size every week.
  4. Trace mix. Fe % defaults to the Plantex CSM+B label (6.53%). A different mix needs its own iron %.