Analysis of the ADA nutrient dosing approach

Why study the ADA dosing system?

The ADA dosing approach is one of many commercial systems available, but it is very commonly used and stand in stark contrast to the EI dosing approach because of the nutrient levels used - much much lower. It is a good comparison to the EI system because we can find many successful tanks run on both systems - so the variables and results are well known and easy to compare. Many commercial systems fall between the ADA approach (which is very lean in terms of water column dosing) and the EI dosing approach (which doses more heavily than any commercial system).

So studying both approaches will give you a sense of the range in which tanks can run. Some tanks will run better with one approach than the other. 

Lean Water + Rich Substrate 

The ADA system relies on a rich substrate as a base, while the amount of nutrients dosed into the water column is much more lean. The water column dosage is high in potassium and contains iron, but contains much lower amounts of NO3/PO4. Many of these tanks will show 0 ppm NO3 in their water column when tested. Plants will get their nitrogen supply mainly from the ammonia rich soil. As the soil decomposes (6-12 months), such tanks will naturally become nitrogen limited and growth will slow down (which may not be a bad thing). Additional new Soil & Root tabs are added to enrich the soil as it ages.

The lean dosing system is rooted in Asian principles that aim to reduce excess, with the idea that while higher NO3/PO4/Fe levels alone are rarely a trigger for algae (whose main trigger is organic waste/debris, unhealthy plants, excessive light, etc.), they can indeed exacerbate existing algae problems. Potassium has no effect on algae, even at high levels, so the system takes liberties with dosing.

A weekly cumulative dose of nutrients using ADA's Liquid Fertilization System1 would result in approximately
NO3 - up to 0.7 ppm mixture of NO3/NH3
PO4 - up to 0.6ppm
K - up to 25ppm
Fe/traces - up to 0.06 ppm

The decimals have been checked and there is no error. According to the above, EI's NO3 dosing rate into the water column is about 28 times that of ADA's system. This is partly due to the very rich substrate that ADA aquasoil provides as a counterbalance to the lean dosing in the water column.

A very lean water column makes it easier to maintain algae-free tanks in sparsely planted tanks. This is why hardscape-oriented, sparsely planted tanks used in aquascaping competitions do well under this regime. It is also an easy way for beginners. Growth is slower compared to tanks with rich water column fertilization, but the tanks are generally much more stable. This method has proven so successful that ADA has become one of the largest brands in the planted tank world.

With substrate feeding, each plant has access to nutrients in its own section of soil, while water column nutrients are free for all. The aggressive, faster growers will grab what they can when they can.

The downside of relying so heavily on substrate fertilization is the cost (large quantities of aquasoil quickly become very expensive) and the need to manage and enrich the soil over time.

One point to note is that the success of ADA tanks as a whole is not due to their nutrient dosing approach. (which is not particularly sophisticated) It is mostly due to their top-notch maintenance routine; regular water changes, cleaning and skimming of debris, and husbandry skills to properly trim and position plants. ADA tanks also tend to select easy-to-grow plants that grow well in a wide range of conditions; many of their tanks contain Java fern and Anubias, Cryptocoryne species. The use of easy-to-grow plants combined with good design results in tanks that are aesthetically pleasing yet easy to maintain.

SUMMARY OF PROS AND CONS

ADVANTAGES

• The reliance on rich substrate means less time and effort juggling water dosing/water parameters.
• Water dosing can be reduced greatly, both in frequency and amount. Less heavy water column dosing means less issues with certain algae types such as green dust and green spot algae on hardscape/glass. 
• Easy method for newer aquarists as this approach require less sophistication on managing water column fertilization.
• Nitrogen limited tanks give deeper reds for certain plant species (Rotala rotundifolia, Ludwigia arcuata, Limnophila aromatica etc)
• Controlled growth rates may make plant arrangement easier for aquascaping purposes.

DISADVANTAGES

• Substrate depletes over time, and requires management/enrichment.
• Very lean water column means non-rooted plants may not grow as robust.
• If conditions are too lean, unhealthy plants give rise to algae issues. Many aquarists may not be experienced enough to spot deficiency issues until it manifests as something serious such as a large algae outbreak. 
• Certain species respond well to higher amount of nutrients in the water column and do less well in such setups.
• Plants become very sensitive/vulnerable to root zone disturbances.

Should I use the ADA approach to dosing?

Tanks that are suitable for the ADA dosing approach:

• Planted tanks that are hardscape heavy while being sparsely planted benefit from leaner water column.
• Your priority is to keep hardscape and glass free of algae.
• Tank consists of plants that are able to take nitrate limitation / lean dosing; slower growers and easier species.
• Red plants that color up well with nitrate limitation.
• Iwagumi tanks do especially well with this approach.
• Non-CO2 injected low tech tanks with easy plants.
• If you want to slow down growth rates for easily maintenance. 

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

• If you keep more difficult species that do better with more nutrients in the water column.
• If you want to grow/propagate plants faster.
• If you do not want to spend effort handling substrate enrichment.
• If you have consistent nutrient deficiency issues; plants have thin stems, small leaves.

Click here to see great examples of Iwagumi tanks.

Click here to learn how to grow red aquarium plants.

¹ ADA Green Brighty Special LIGHTS series (before 2018)