PPS-Pro — the Perpetual Preservation System — is the dosing method for people who looked at EI's weekly 50% water changes and thought, "absolutely not." Developed by hobbyist Edward (writing as "Edward" on the Aquatic Plant Central forums), PPS-Pro takes the opposite approach to the Estimative Index: instead of dosing in excess and flushing weekly, you dose small daily amounts calibrated to what plants actually consume, and water changes drop to a modest monthly routine. It's the thinking person's method — a little more measuring, a lot less hauling buckets.
This guide explains how PPS-Pro works, the exact daily doses, how to mix the solutions, and how to tune it to your tank.
What PPS-Pro Is (and What Problem It Solves)
Every fertilization method is a trade-off between precision and maintenance. EI chose abundance + big water changes. PPS-Pro chose precision + small water changes. The method's full name — Perpetual Preservation System, Professional — hints at its goal: a perpetual steady state where nutrient levels hold constant week after week, preserved by daily micro-dosing that exactly replaces what plants consumed the day before.
In practice, PPS-Pro keeps your water column at lean, stable levels: roughly 5–10 ppm nitrate, ~1 ppm phosphate, ~10 ppm potassium, and ~0.1 ppm iron. Compare that to EI's 20+ ppm nitrate, and you see the philosophical difference immediately. PPS-Pro doesn't try to eliminate limitation through excess — it tries to match supply to demand so precisely that limitation never quite arrives.
Who is it for? Low-tech and medium-tech tanks first and foremost — setups where plant uptake is moderate and predictable. It's also ideal for anyone who can't or won't do large weekly water changes: apartment dwellers without Python-style changers, shrimp breeders who value stability, and multi-tank keepers who'd rather dose daily from a bottle than flush every tank every Sunday.
The Standard PPS-Pro Daily Dose
PPS-Pro is built around two stock solutions — a macro solution and a micro solution — dosed every day before the lights come on. The standard dose is 1 ml of each solution per 10 gallons (38 liters) of tank water, daily.
That's it. One milliliter of macros, one milliliter of micros, every morning. For a 20-gallon tank: 2 ml of each. For a 40-gallon: 4 ml of each. A standard medicine syringe or a pump bottle (most dosing pumps deliver 2 ml per pump) makes this a ten-second ritual.
The macro solution (500 ml bottle)
- 500 ml distilled water
- 33 g potassium sulfate (K₂SO₄) — the potassium source
- 33 g potassium nitrate (KNO₃) — the nitrogen source
- 3 g potassium phosphate (KH₂PO₄) — the phosphorus source
- 20 g magnesium sulfate (MgSO₄, Epsom salt) — the magnesium source
The micro solution (500 ml bottle)
- 500 ml distilled water
- 40 g CSM+B or equivalent trace mix
- A few drops of acid or a pinch of ascorbic acid as preservative (trace solutions can grow mold over months)
Mix each in its own bottle with distilled water, shake until dissolved, and dose separately — never combine macros and micros in one bottle, since iron and phosphate precipitate together into unavailable sludge. This is the same chemistry rule as in EI, and it applies to every dosing method that uses both.
At 1 ml per 10 gallons daily, a 500 ml bottle lasts a 20-gallon tank about four months. The dry salts to mix a year's supply cost roughly what one bottle of premium liquid fertilizer costs — the economics of dry vs. liquid fertilizers strongly favor mixing your own once you're past the beginner stage.
Position as the one-pump daily alternative that captures PPS-Pro's low-dose spirit without mixing stock solutions: NilocG Thrive all-in-one.
Why Daily Dosing Changes the Game
The daily rhythm is PPS-Pro's real innovation, and it matters for three reasons:
- Stability. Plants get a fresh, identical meal every morning instead of a feast-and-famine cycle. Nutrient levels in the water barely move day to day, which is exactly the kind of boring stability that prevents algae. Algae thrives on fluctuation; PPS-Pro starves it of drama.
- No accumulation math. Because you're replacing only what was consumed, levels don't ratchet upward over time. That's what makes the monthly (instead of weekly) water change possible — there's simply less excess to flush.
- Early warning. Dosing daily means you're looking at your tank daily. Deficiency symptoms get caught at the "hmm, that leaf looks off" stage instead of the "why is everything melting" stage. The method quietly trains observation.
The obvious cost is the daily commitment. Missing a day occasionally is harmless — the lean levels mean one skipped dose won't crash anything — but if daily rituals don't fit your life, an all-in-one fertilizer dosed a few times a week will serve you better than PPS-Pro done sporadically.
Setting Up: The First Two Weeks
Don't just start dosing blindly. PPS-Pro works best when calibrated to your actual tank, and the calibration takes about two weeks:
Week 1: Baseline
Before your first dose, do a large (50%) water change and test your tap water for nitrate and phosphate so you know your starting point. Then begin the standard daily dose: 1 ml per 10 gallons of each solution. Dose macros and micros at the same time each morning — order doesn't matter as long as they're diluted into the full tank volume, not mixed concentrated in a cup first.
Week 2: Read and adjust
At the end of week one, test nitrate and phosphate before the morning dose. You're aiming for the PPS-Pro target zone: nitrate 5–10 ppm, phosphate around 0.5–1 ppm. Then adjust:
- Nitrate below 5 ppm: Your plants are hungrier than the standard dose. Increase the macro dose by 50% (1.5 ml per 10 gallons) and retest in a week.
- Nitrate climbing past 15 ppm: Your bioload is contributing nitrogen (fish waste counts as fertilizer). Reduce or eliminate the KNO₃ in your next macro batch — you can mix a fish-heavy-tank variant with extra K₂SO₄ to keep potassium up while dropping nitrogen.
- Phosphate near zero with good nitrate: Bump the KH₂PO₄ slightly in the next batch. Persistent zero phosphate with green-spot algae on slow growers is the classic sign.
- Everything in range: Don't touch anything. The hardest PPS-Pro skill is leaving a working recipe alone.
After 2–3 rounds of testing and tweaking, most tanks settle into a stable recipe that runs untouched for months. Testing is front-loaded — once calibrated, you can put the kits away and just dose.
Suggest as the conservative starter dose for the first two weeks before ramping to full PPS-Pro levels: API Leaf Zone.
PPS-Pro for Different Tank Styles
Low-tech tanks (no CO2, moderate light)
This is PPS-Pro's sweet spot. Uptake is slow and steady, the standard dose usually lands close to correct on the first try, and the monthly water change schedule is a genuine lifestyle upgrade over EI. If you're growing without CO2, start here before considering anything more aggressive.
High-tech tanks (CO2 injection, strong light)
PPS-Pro can run high-tech tanks, but it needs scaling up — sometimes 2–3x the standard dose — and at that point you're doing daily measuring to achieve what EI does with a weekly scoop. Many high-tech keepers start on PPS-Pro, get tired of the daily syringe ritual at triple doses, and migrate to EI dosing. That's a natural progression, not a failure.
Shrimp and breeding tanks
PPS-Pro's lean, stable levels are beloved in the shrimp world. Big water changes stress shrimp; fluctuating parameters trigger failed molts. PPS-Pro's monthly small-change routine and rock-steady chemistry are about as shrimp-friendly as fertilizing gets. Dose in the morning, keep the recipe consistent, and your colony will thank you.
New aquasoil tanks
Fresh aquasoil leaches ammonia and nutrients for the first month — dosing full PPS-Pro on top of that is piling fertilizer on fertilizer. Start at half dose (or dose micros only) for the first 2–3 weeks, then ramp to full as the soil settles. Our new aquasoil fertilizing guide maps out the week-by-week ramp for exactly this situation.
Fine-Tuning: The PPS-Pro Mindset
Once calibrated, PPS-Pro runs itself — but tanks change. Plant mass grows, fish get added, light fixtures get upgraded. Recalibrate (one week of testing) whenever:
- You do a major rescape or add/remove a lot of plant mass
- Your fish stocking changes significantly
- You upgrade lighting or start/stop CO2
- Algae appears out of nowhere in a previously stable tank — something shifted, and the recipe needs to follow
Common targeted tweaks from experienced PPS-Pro users:
- Extra iron for red plants: The standard micro solution keeps iron around 0.1 ppm, which is enough for green growth but lean for intense reds. A separate iron dosing routine on top of PPS-Pro micros is the usual fix — dose iron on alternate days from the micro mix to avoid precipitation issues.
- Potassium bumps: Fast stem-plant tanks sometimes show pinholes despite textbook PPS-Pro numbers. A small separate K₂SO₄ dose (dry, twice weekly) fixes it without disturbing the calibrated recipe.
- Magnesium in soft water: The macro solution includes Epsom salt, but very soft tap water plus heavy plant mass can still run lean. If new growth twists or interveinal chlorosis appears, bump the MgSO₄ in the next batch.
PPS-Pro vs. EI: Honest Comparison
| PPS-Pro | EI (Estimative Index) | |
|---|---|---|
| Dosing frequency | Daily, small amounts | 3x weekly macros, 3x weekly micros |
| Water changes | Monthly, ~25–30% | Weekly, 50% |
| Nutrient levels | Lean and stable (NO₃ 5–10 ppm) | Rich with safety margin (NO₃ ~20 ppm) |
| Test kits | Needed for initial calibration | Not needed (by design) |
| Best for | Low/medium-tech, shrimp tanks, small-change lifestyles | High-tech CO2 tanks, heavy plant mass |
| Forgiveness | Less forgiving of recipe errors | Very forgiving — excess covers mistakes |
| Daily effort | ~1 minute every morning | ~1 minute, 6 days a week |
Neither method is "better" — they optimize for different lives. The right question isn't which is superior, it's: will I actually do weekly 50% water changes? Answer honestly, then choose. Our fertilizer schedule overview puts all the methods side by side if you're still deciding.
Frequently Asked Questions
What if I miss a day of dosing?
Nothing bad happens. PPS-Pro's lean levels mean one missed day just means slightly leaner levels for 24 hours — plants won't even notice. Two or three missed days in a row might slow growth marginally in a high-demand tank. Just resume the normal dose; don't double up to "catch up," since that defeats the steady-state logic.
Can I mix the macro and micro solutions into one bottle?
No. The iron in the trace mix reacts with phosphate in the macro mix and precipitates out as unavailable sludge — you'd be dosing cloudy water with the good stuff sitting at the bottom. Two bottles, always. You can dose them into the tank at the same time (the full tank volume dilutes them instantly), just never store them concentrated together.
How do I know my recipe is calibrated correctly?
Two signs: your nitrate and phosphate tests hold steady week to week (not climbing, not crashing to zero), and your plants grow steadily without deficiency symptoms. Stable tests plus healthy plants equals a calibrated tank. If tests are stable but plants show deficiencies, the issue is usually something PPS-Pro doesn't dose — CO2, light, or GH minerals.
Is PPS-Pro safe for shrimp and snails?
Yes — it's one of the most shrimp-friendly fertilizing methods precisely because levels stay low and stable. The trace mix contains tiny amounts of copper, but chelated and at concentrations far below what's harmful to invertebrates. Countless shrimp breeders run PPS-Pro as their standard. Stability matters more to shrimp than absolute nutrient levels, and stability is this method's whole identity.
Can I use tap water to mix the stock solutions?
It's not recommended. Tap water contains chlorine/chloramine and dissolved minerals (especially calcium and iron) that can react with the concentrated salts, cause precipitation, or feed mold growth in the bottle. Distilled or RO water costs little and keeps solutions stable for months. If you must use tap water, dechlorinate it first and expect a shorter shelf life.
When should I switch from PPS-Pro to EI?
Consider the switch when your tank outgrows PPS-Pro's comfort zone: you add CO2 and strong light, plant mass explodes, and you find yourself dosing 3x the standard recipe just to keep nitrates above zero. At that point EI's "dose in excess and flush weekly" becomes less work than precision-dosing a hungry tank. Many hobbyists run PPS-Pro for years on low-tech tanks and never need to switch — it's a destination, not a stepping stone.
The Quiet Power of Routine
PPS-Pro doesn't promise explosive growth or record-breaking reds. It promises something rarer in this hobby: a tank that looks the same healthy way every single week, maintained with a one-minute morning ritual and a water change you barely have to think about monthly. Mix your two bottles, calibrate once, and let the steady state carry you. Boring chemistry is beautiful chemistry.