Target-ppm dosing across all aquarium system types — planted, reef, fish-only, brackish, paludarium and hybrid. Complete compound database, diagnostic intelligence, 30-day simulation, risk engine and biological layer modelling.
Enter your current test results. Leave blank for untested parameters.
Select all compounds for your regime. Set the ppm rise per dose and bottle/dose volumes. The calculator outputs the full recipe for every compound at once.
Model how your parameters evolve over 30 days given your dosing schedule, water changes, fish load and plant consumption.
Enter all current readings. The engine cross-references known chemical interactions, antagonisms, toxicity risks and ionic imbalances.
Select your aquarium system type and enter your tank volume at the top. The calculator automatically loads the correct target parameters and compound database for your setup — planted tanks, reef systems, fish-only tanks and paludariums all have different requirements.
Use the module tabs to navigate between functions. Each module saves your inputs — switching tabs will not clear your work. Start with Module 1 (Parameter Status) to enter your current readings and see what needs adjusting.
For each deficient parameter, Module 2 (Raise to Target) calculates the exact compound dose required. Module 3 handles maintenance dosing once you've reached your targets. For reef tanks, Module 4 handles two-part dosing and kalkwasser.
The 30-Day Simulation (Module 7) models how your parameters will evolve over time based on your dosing plan — useful for planning a new tank or correcting chronic deficiencies without overshooting.
Target ranges vary significantly between system types. Using reef targets in a planted tank — or vice versa — is a common cause of chronic deficiencies or toxicity. The calculator loads these automatically, but the table below is a useful reference.
| System type | Key parameters | Nitrate (NO₃) | Phosphate (PO₄) | Redfield focus |
|---|---|---|---|---|
| FW Hi-tech planted | N, P, K, Fe, Mg, Ca | 5–20 ppm | 0.1–1.0 ppm | Yes — N:P ratio critical |
| FW Low-tech planted | N, P, K (light) | 5–15 ppm | 0.05–0.5 ppm | Optional |
| Discus planted | N, P, K, soft water | 2–10 ppm | 0.05–0.3 ppm | Yes |
| Fish-only freshwater | Minimal dosing | <20 ppm | <1.0 ppm | No |
| Reef — soft corals | Alk, Ca, Mg | <10 ppm | <0.1 ppm | No |
| Reef — LPS | Alk, Ca, Mg, K, trace | <5 ppm | <0.05 ppm | No |
| Reef — SPS | Alk, Ca, Mg, K, trace elements | <2 ppm | <0.02 ppm | No |
| FOWLR / fish-only reef | Alk, Ca (moderate) | <20 ppm | <0.5 ppm | No |
| Brackish | KH, moderate trace | <20 ppm | <0.5 ppm | No |
| Paludarium | N, P, K (substrate zone) | 5–15 ppm | 0.1–0.5 ppm | Optional |
The simplest method — measure liquid concentrate and add directly to the tank or sump. Suitable for all system types. Requires daily or weekly dosing depending on consumption. Lower upfront cost, higher ongoing effort. Most accurate for small volumes.
Two separate solutions — one for alkalinity, one for calcium/magnesium — dosed simultaneously to maintain balance. The most popular reef method. Can be automated with a dosing pump. Scales well with coral consumption. Module 4 calculates two-part volumes.
Saturated calcium hydroxide solution added as top-off water. Raises both calcium and alkalinity simultaneously while precipitating phosphate. Suitable for low-to-medium coral consumption. Higher risk if overdosed — do not use with auto top-off systems without proper controllers.
Perpetual Preservation System — daily micro-dosing of separate macro and micro nutrient solutions. Maintains near-zero surplus so algae has nothing to exploit. Requires consistent daily dosing; skipped doses cause parameter swings. Effective for high-light, high-CO₂ setups.
Deliberately doses above plant demand and relies on a large weekly water change (50%) to reset. Simple, forgiving, and resistant to deficiency. Algae is controlled by the regular reset, not by dialling nutrients. Best for high-growth setups where testing is infrequent.
Peristaltic pumps dose precise volumes on a schedule. Reduce daily effort significantly. Requires calibration and regular pump head replacement. Essential for SPS reefs with high alkalinity consumption. Most effective when paired with regular parameter testing.
Visual symptoms in plants and corals often precede measurable test kit readings. Identifying symptoms early lets you correct deficiencies before they cause permanent damage. Use Module 8 (Diagnosis) for guided assessment.
| Symptom | Likely cause | System | Urgency |
|---|---|---|---|
| Yellowing of older leaves (chlorosis) | Nitrogen (N) deficiency | Planted | Moderate |
| Yellowing with green veins (interveinal chlorosis) | Iron (Fe) or Manganese (Mn) deficiency | Planted | Moderate |
| Purple/red colouration of undersides | Phosphate (P) deficiency | Planted | Moderate |
| Pinholes in leaves, leaf edges yellowing | Potassium (K) deficiency | Planted | Low |
| New growth pale, older growth green | Iron (Fe) deficiency | Planted | Moderate |
| Coral tissue recession (RTN/STN) | Alk swing, low Ca, or pathogen | Reef | High |
| Coral bleaching (white tissue) | Temperature spike, low Alk | Reef | High |
| Coral paling (less vibrant colour) | Low trace elements, high NO₃/PO₄ | Reef | Moderate |
| Coral polyps not extending | Low flow, copper contamination, alk swings | Reef | Moderate |
| Black beard algae (BBA) | CO₂ fluctuation — not nutrient deficiency | Planted | Investigate CO₂ |
| Green spot algae (GSA) | Low phosphate relative to light level | Planted | Low |
⚠ Many deficiency symptoms overlap with other problems (disease, flow issues, lighting). Always cross-reference with test kit readings before dosing. The Diagnosis module (M8) and Interaction Checker (M9) help rule out false positives.
The calcium-carbonate-magnesium triad is the foundation of reef chemistry. Corals extract calcium and carbonate ions from the water to build their skeletons — the rate depends on coral species, light intensity, and colony size. As coral mass increases, daily consumption increases with it.
Alkalinity (dKH) stability is more important than its absolute value. A swing of even 1–2 dKH per day can stress or kill SPS corals. Dose alkalinity in small increments throughout the day — never add large boluses directly to the display tank.
Magnesium maintains the balance between calcium and alkalinity. Low magnesium causes calcium and alkalinity to precipitate out of solution at lower values than expected — if you cannot hold Ca above 380 ppm without precipitation, check Mg first. Target 1250–1350 ppm.
The ratio Ca:Alk:Mg follows approximately 400:8:1280 (in ppm:dKH:ppm). The calculator enforces these ratios in Module 4 and flags imbalances in Module 9. Always correct large imbalances in stages — raising Ca by 100 ppm in a single dose risks precipitation.
All dose calculations in this calculator use purified compound concentrations. Real-world products vary — always read your product label and cross-reference the concentration before dosing.
Never dose multiple chemicals simultaneously in the same area of the tank. Calcium and alkalinity solutions precipitate if they meet at high concentration — always dose on opposite ends of the tank or sump, or at different times.
Raise deficiencies in stages. If a parameter is severely low, correct it over 3–5 days rather than in one large dose. Rapid changes stress fish and corals even when the target value is correct.
Test before and after dosing. Do not rely solely on calculated doses — reagent test kits and/or ICP testing are essential to confirm results. Consumptions vary with bioload, coral mass, plant growth rate, and water change frequency.
Potassium permanganate and copper compounds are toxic to invertebrates, plants, and beneficial bacteria at elevated levels. Use Module 9 (Interactions) to screen for conflicts before adding new compounds to an established regimen.
Use the dosing calculator alongside our other tools for a complete picture of your aquarium's needs.