Lean Dosing Weekly Schedule Guide: Targets and Mixing
The pendulum has swung — 2hr Aquarist’s lean dosing approach now dominates competition aquascapes that once ran on EI. Lean dosing planted tank philosophy keeps water-column nutrients deliberately low, forcing plants to draw from the substrate and producing tighter inter-node growth and deeper red pigments. This guide from Gensou Aquascaping at 5 Everton Park covers the weekly schedule, target ppm windows, and mixing instructions that work cleanly with Singapore PUB tap water.
The Lean Philosophy
Where EI doses to surplus, lean dosing aims for 5-10 ppm NO3, 0.1-0.5 ppm PO4, 5-10 ppm K, and 0.05-0.1 ppm Fe at peak — roughly one-fifth of EI levels. The bet is that mature aquasoil holds more than enough nitrogen and phosphorus for most plants, and water-column traces only need to top up potassium and iron. Reds intensify because phosphate competes with iron uptake; less PO4 means redder Rotala.
Who Should Run Lean
Lean dosing suits matured tanks (six months plus) on fresh aquasoil, with light-to-moderate stocking and slow-growing or red-heavy plant lists. It is not for new setups — aquasoil leaches ammonia for the first six weeks regardless of dosing, and plants need water-column N until roots establish. Stem-tank Dutch styles with fast nutrient burn-rates also run too lean to keep up; those need EI or hybrid dosing.
Target Concentrations Compared
Lean targets per week: NO3 5-10 ppm, PO4 0.1-0.5 ppm, K 5-10 ppm, Fe 0.05 ppm, Mg 5 ppm, Ca 15 ppm, GH 4-6. Compare to EI’s NO3 20-30 ppm and PO4 3-6 ppm — the difference is an order of magnitude on phosphate. Test weekly with reagent kits; lean tanks reveal deficiencies fast and need correction within days, not weeks. A reliable water test kit set is non-negotiable.
Dry Salt Recipe for 200 Litres
Weekly dose for a 200-litre lean setup: 1.5 g KNO3, 0.06 g KH2PO4, 1 g K2SO4, 0.1 g iron chelate (Fe-DTPA or Fe-EDDHA), 0.1 g CSM+B trace. Phosphate is so small here that pre-dissolving in 500 ml of RO water gives 0.12 mg/ml stock, dosed at 0.5 ml three times weekly. A 0.001 g precision scale is overkill but useful — most hobbyists pre-mix into liquid concentrates to avoid weighing micrograms.
Daily vs Weekly Splits
Lean schedules favour daily micro-doses over the EI three-day macro split. Reason: water column targets are so low that a single weekly dump spikes briefly past safe thresholds for sensitive species. A peristaltic dosing pump running 1 ml of macro stock daily and 0.5 ml of micro stock daily holds the column flat. Manual lean dosing means every-other-day topping with smaller volumes.
Sample Weekly Schedule
Day 1 (water change day): 30 per cent change, GH booster to 5-6, no fert dose. Day 2: macro 1 ml, micro 0.5 ml. Day 3: macro 1 ml. Day 4: macro 1 ml, micro 0.5 ml. Day 5: macro 1 ml. Day 6: macro 1 ml, micro 0.5 ml. Day 7: macro 1 ml. Photoperiod and CO2 stay constant — lean is a fertiliser concept, not a light or carbon strategy.
Singapore Tap Water Considerations
PUB water arrives soft (GH 2-4, KH 1-2), low in calcium and magnesium. Lean dosing on unmodified tap will starve plants of Ca within four weeks. Add Salty Shrimp GH+ or a homebrew CaSO4:MgSO4 (3:1 ratio) to lift GH to 5-6 at every change. Skip baking soda — KH bumps interfere with the soft-water profile most stems prefer.
Reading Lean Plants
Healthy lean tanks show short inter-nodes, compact growth, deep colour saturation, and minimal pearling on most stems. Yellow lower leaves on Rotala usually mean nitrogen is too lean — bump weekly NO3 to 8-10 ppm. Tip curl on Bucephalandra or Anubias means calcium deficit; lift Ca to 20 ppm. Pinholes on Cryptocoryne indicate potassium starvation — that one is universal across dosing styles.
Switching from EI to Lean
Cold-switching from EI to lean shocks plants. Reduce doses by 25 per cent each week over four weeks, increase water change frequency to twice weekly during the transition, and watch for algae blooms as decaying leaves release stored phosphate. Pair with root tabs from the root tab range in the substrate to compensate for the reduced water column feed during the changeover.
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