2Hr Aquarist APT e is a ready-to-use, comprehensive fertilizer based on the Estimative Index (EI) method, providing all essential macro and micronutrients for heavily planted aquariums
✅ APT products ship free on orders $20+ Refunded @ Shipping
Price range: $11.80 through $50.90
Precision nutrition for high-performance planted tanks.
APT Estimative is a concentrated fertiliser built on the Estimative Index (EI) approach pioneered by Tom Barr. Unlike traditional “unlimited” EI-style dosing, APT e provides a more refined balance—delivering enhanced coloration, stronger growth, and cleaner tanks.
This formula is engineered for aquarists who understand EI fundamentals and want to push the boundaries of visual performance while avoiding unnecessary nutrient excess.
2× more nitrate-limiting for richer coloration*
2× more magnesium for stronger structural growth^
Highly concentrated: 500ml lasts ~3 months for a 150L tank
Refined EI dosing with better uptake, less waste
Formulated for CO₂-injected, high-light tanks
*Compared to conventional EI formulas based on NPK balance per ml
^Based on magnesium content per ml relative to common EI mixes
Daily Dose: 2ml per 100L
Yield: 500ml = ~250 doses
Pump not included
APT Estimative is suitable for tanks with strong lighting, consistent CO₂ injection, and a high density of aquatic plants. It is not recommended for low-energy tanks or beginner setups.
| Nutrient | Concentration |
|---|---|
| Total Nitrogen (N) | 2.00% |
| – Nitrate Nitrogen | 2.00% |
| Available Phosphoric Acid (P₂O₅) | 1.37% |
| Soluble Potash (K₂O) | 8.00% |
| Magnesium (Mg) | 1.60% |
| Iron (Fe) | 0.16% |
| – Chelated Iron (Fe) | 0.16% |
Derived from: Potassium Sulphate, Potassium Phosphate, Potassium Chloride, Magnesium Nitrate, Magnesium Sulphate, DTPA Iron, EDTA Iron, EDDHA Iron.
APT e is not just more concentrated—it’s more absorbable. Compared to older-generation fertilisers:
5× more phosphorus per ml
6× more potassium per ml
Up to 50× greater uptake efficiency across wider pH and water conditions
This isn’t just a boost in numbers—it’s a boost in real-world plant response.
APT e is ideal if you:
Understand EI dosing and want better color and growth
Have a high-light, CO₂-injected tank
Maintain stable water parameters and regular maintenance
Want a cleaner, more efficient approach to EI fertilization
What kind of tank is APT Estimative designed for?
APT Estimative is best suited for high-energy planted tanks — setups with strong lighting, consistent CO₂ injection, and a dense variety of stem and carpeting plants. It’s ideal for aquascapers who enjoy active tank management and want precise control over growth and coloration.
How is this different from standard EI dosing?
While traditional Estimative Index (EI) methods aim to supply nutrients without limit, APT Estimative refines that approach. It balances nutrient ratios with higher bioavailability, resulting in vibrant growth and rich coloration — without excess. It’s a smarter, more targeted way to dose.
Can I switch to APT Estimative from another fertiliser?
Absolutely. Many aquarists transition from all-in-one blends or lean dosing to APT Estimative to unlock the full potential of their plants. A gradual shift over a week or two helps plants adjust smoothly while maintaining consistent performance.
How soon will I see results?
Most users notice stronger, healthier new growth within the first 7–14 days. Improvements in color, plant density, and root strength follow as the tank stabilizes around the new dosing rhythm.
Does APT Estimative support red plants?
Yes. APT e’s nitrate-limiting ratio and added magnesium support deep reds and purples in species like Alternanthera, Rotala, Ludwigia, and others. When paired with proper lighting and CO₂, the results are striking.
Is this suitable for beginner tanks or low-tech setups?
APT Estimative is formulated for high-performance aquascaping. For lower-energy or low-maintenance tanks, APT 1 or APT 3 may be more appropriate options — offering balanced nutrition with a simplified approach.
