PPS-Pro dosing explained
PPS-Pro is the opposite philosophy to EI: dose small amounts daily, close to what plants use, and let conductivity (TDS) tell you when to change water.
How it works
The method's author publishes a two-bottle system: a macro bottle and a trace bottle dosed together every day before the lights come on. The published medium-light starting rate is 1 mL of the macro bottle per 10 gallons (about 40 L) per day, stated to add about 1 ppm NO₃, 0.1 ppm PO₄, 1.33 ppm K and 0.1 ppm Mg per day. Low light halves it; very high light doubles it.
The published 500 mL macro recipe
29 g K₂SO₄, 33 g KNO₃, 3 g KH₂PO₄ and 20 g MgSO₄ in 500 mL. Our unit tests check that our engine reproduces the stated per-dose ppm from that recipe within rounding.
EI vs PPS-Pro
| EI | PPS-Pro | |
|---|---|---|
| Dose size | Generous, 3×/week | Small, daily |
| Water change | 50 % weekly, required | Guided by TDS/conductivity |
| Weekly NO₃ added | ~20–30 ppm | ~7 ppm (medium light) |
| Best for | High light + CO₂, fast growth | Keepers who want lean water and fewer big changes |
Open PPS-Pro style in stock mode. Our preset approximates the published medium-light rate; adjust targets for your light.
Open the dosing calculatorMore guides
Sources
- Perpetual Preservation System: chemicals and dosing
- Perpetual Preservation System: PPS-Pro recipe
- Barr Report: EI for comparison
Written in our own words from the sources above. Numbers are educational starting points; check product labels and your water.