Above: a colorful bouquet grown The 2Hr Way using APT 3 ("APT Complete")
Do we really need fertilizers for a planted aquarium?
If you want an ecosystem with thriving plants, the answer is yes. If you are keeping only fish or specific livestock, probably no.
This is because aquatic plants need a full set of nutrients to thrive (not surprisingly) and the tank's eco-system is incomplete. Fish waste and decomposing matter can provide some amounts of nitrogen and phosphates, but sorely insufficient amounts of potassium, iron and other minerals. Using soil (the real organic stuff) provides a source of nutrition that can last a few months, but is depleted after that.
There is a tendency to compare our aquarium with 'nature' , forgetting that the minuscule world we have created is only a tiny selective slice of nature and far from 'self-balancing'. And while we seek to replicate nature, what we really want is a particular (and often un-natural) instance of nature. We want lush, thriving plants and a lively livestock population without algae in crystal clear water....contained in a tiny high-density space. Such environments do occur naturally in the wild, but often only in specific seasons and circumstances, while we want the same instance to be constant and never-changing in our planted tank!
What fertilizer should I use?
It really depends on your objectives. While there are countless brands of fertilizers in the market, the concentration and relative ratios of minerals in them vary greatly.
90% of common brands available off-the-shelf are designed for casual 'fish tank' hobbyists, where plants are mostly secondary.
Hobbyists looking to support a thriving planted ecosystem have generally had to combine a variety of different fertilizers to obtain a better spread and concentration of nutrition to support richer colors and stronger growth. For more serious planted aquarists, it is often a painstaking process of combining sometimes more than 10 different individual components (N, P, K, Iron, Magnesium and other trace elements) in order to unlock superior coloration and form. The 2Hr Aquarist APT range of fertilizers originated from this process, and were developed specifically to make this process faster, cheaper and less error prone, by offering powerful all-in-one formulations with the right balance and concentration.
Above: a Tank using the Estimative Index approach, by Tom Barr
Many professional aquarists in the US gravitate towards the Estimative Index approach to providing nutrition, which is a methodology based on providing the tank with more than the maximum estimated nutrition that plants require. EI Style tanks are known for their colorful, nutrient-demanding plants. This heavy dosing approach comes with significant algae risk (due to the high levels of nitrates and phosphates) and requires a high level of plant husbandry skill to be used effectively. The APT Estimative Index formula makes it easy for aquarists to execute this dosing methodology through a simple all-in-one concentrate. Read more about the Estimative Index methodology here.
Above: a 'Nature Style' 2Hr Tank using APT 1 ("APT Zero")
In Asia, many serious aquarists in the 1990s followed the ADA approach, popularised by Takashi Amano. In contrast to the Estimative Index approach, the ADA approach is super-lean, relying instead on a rich soil substrate (vs tanks on Estimative Index, which often use sand/ inert substrates) to provide nutrition. ADA 'nature style' tanks grow more slowly and are known for their relative ease of maintenance and longevity. Importantly, they are predominantly 'green' and feature far less color. APT 1 (APT Zero) was designed for aquarists to easily execute the ADA approaching to dosing, through an all-in-one formulation.
Above a 2Hr 'Farm Tank' using APT 3 ("APT Complete").
APT 3 (APT Complete)came about because we wanted a middle ground. We sought to grow the colorful, nutrient- demanding plants found in Estimative-Index style tanks, but with less incidence of algae and easier maintenance. ADA's extremely lean approach was too lean to support these plants, especially after the natural depletion of soil nutrition over a couple of months. 2Hr Tanks are characterized by lush growth with a splash of color, with relatively simple maintenance.