2HR Aquarist - APT E Estimative Index

With the 2HR Aquarist APT-EI, the famous nutrient dosing approach pioneered by Tom Barr is now available in a ready-to-use concentrate that removes the guesswork from trying to recreate this powerful and sometimes elusive formula.

Quantity: 2


APT e is perfect for heavily planted Dutch Style tanks and users who understand EI methodology. Supremely concentrated and expertly balanced.

Dose 5ml per 100L 3 times per week or 2ml per 100L daily


Should I use Estimative Index dosing?


Tanks that are suitable for EI dosing approach:


  • If you have a very fully planted tank (>70% of substrate planted).
  • Tank consists of plants that grow more robust in heavy water column fertilization; (i.e. Ludwigia pantanal & other heavy feeders).
  • If you plan to farm plants and hence want faster growth rates.
  • If you can keep up with the increased trimming/maintenance associated with faster growth rates.
  • If you are rushing to complete a project, and need maximum growth speed.
  • If you are good at tank maintenance and have a very clean tank with few triggers for algae.


Tanks that will probably do better on a leaner dosing approach:


  • If you have a hardscape heavy setup with light planting.
  • If your tank consists of mostly slow growers and your priority is to keep them spotlessly clean.
  • If your priority is tank stability and you want slower more controlled growth speed in plants.
  • If you have persistent green dust algae issues.
  • Non-CO2 injected tanks.
  • If you have hardwater and are facing tip stunting issues with Lythraceae (Various Ammania, Rotala species, Pogostemon erectus, etc).

Available in 200ml, 300ml, 500ml, 1L

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