The PPS-Pro recipe and dosing schedule
The classic two-bottle mix, the exact salt weights, and how much to dose.
PPS-Pro (Perpetual Preservation System) is a two-bottle dry-salt fertilizer system designed to feed a planted tank roughly at the rate the plants consume — so little accumulates and big water changes become optional. The recipe has been stable since around 2007. Here it is.
The two bottles
Each bottle is mixed into 500 mL of distilled or RO water:
| Macros bottle (per 500 mL) | Amount |
|---|---|
| Potassium nitrate (KNO₃) | 33 g |
| Potassium sulfate (K₂SO₄) | 29 g |
| Magnesium sulfate (MgSO₄ · Epsom) | 20 g |
| Mono-potassium phosphate (KH₂PO₄) | 3 g |
| Micros bottle (per 500 mL) | Amount |
|---|---|
| Trace-element mix (CSM+B or equivalent) | 29 g |
The dose
Dose 1 mL of each bottle per 10 gallons of tank water, daily.
Both the macros and the micros bottle, every day. A 40-gallon tank gets 4 mL of each. Water changes are optional under PPS-Pro — though many people still do a modest weekly change for general maintenance.
Phosphate (from the macros) and trace iron (from the micros) react and precipitate when concentrated together — your iron drops out of solution. Keep them in two separate bottles, as the recipe specifies, and dose each one separately.
Mixing tips
- Use distilled or RO water for the stock solutions — tap water minerals can cause cloudiness or early precipitation.
- A few drops of trace preservative (or refrigerating the micros bottle) slows mold growth over the weeks it takes to use up 500 mL.
- Shake before each dose, especially the micros.
Gear this guide uses
Mixing the two PPS-Pro bottles takes the dry salts, a way to weigh them, and bottles to store them in.
- The macros bottle needs KNO₃, K₂SO₄, MgSO₄, and KH₂PO₄; the micros bottle needs a CSM+B trace-element mix.
- Weigh the grams accurately with a 0.01 g digital scale.
- Keep macros and micros apart in separate dosing bottles.
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Sources
General hobbyist guidance. Verify salt purities and adjust to your plant response; mix and store chemicals safely.