The great debate.... CarbiSea's EcoCompelte versus ADA Amazonia, or any aquasoil to be honest. Can EcoComplete out-perform an aquasoil, like ADA Amazona, in growth?! Dun dun dunnnnn... well I'm here to tell you that an aquasoil will always outperform EcoCompelte when providing nutrients to root feeding plants and I'll explain the science behind why. It all comes down to cation exchange capacity, or CEC, organic matter and humus.
What is Cation Exchange Capacity (CEC)?
We first need to define cation exchange capacity, or CEC. CEC is defined by Perdue University in their research paper Fundamentals of Soil Cation Exchange Capacity (CEC) as "The total number of cations a soil can hold--or its total negative charge--is the soil's cation exchange capacity. The higher the CEC, the higher the negative charge and the more cations that can be held." So what does this mean for our aquarium? CEC is the substrate's ability to absorb nutrients from the water column and provide that nutrients to root feeding plants. The higher the CEC, the more nutrients a substrate can absorb. So high CEC is good for foot feeders, and a low CEC is bad.
So what is the CEC of ADA Amazonia?
Most aquasoils, like ADA Amazonia, are made from rice paddie soil. These types of soils have a CEC of "more than 50", as outlined in Rice Nutrient Management in California. These soils are also packed with organic matter due to "plant and animal residues in various stages of decay, along with their decomposition products". "The primary benefit of decomposing organic matter is the release of organic forms of nutrients through a process called remineralization. This is the "primary source of soil nitrogen, phosphorus and sulfur as ammonium (NH₄⁺), phosphates (PO43-) and sulfate (SO₄²⁻) ions.
The secondary benefit of this decomposing organic matter is the formation of humus, which increases the CEC of the soil and prevents the leaching of certain nutrients (ammonium, nitrogen, potassium, calcium and manganese) into the water column. Humus also acts as chelates which is able to hold on to micronutrients like zinc, iron, copper and manganese. Diana Walstad in her book Ecology of a Planted Aquarium talks about the development and important of humus. Humus develops a denitrifying bacteria which helps keep nitrates low, and detoxify heavy metals ultimately protecting livetstock. Below is a chart of the nutrients that is readily available in a rice paddie soil.
Elemental composition of rice straw after glowing for six seasons under selected stray management practices.
What is the CEC of EcoComplete?
Unfortulety, the CEC of volcanic basalt is really low. Like surprisingly low for how CarbiSea markets the substrate. The study Environmental Nanotechnology, Monitoring & Management found that the average CEC for four volcanic basalt samples was 9.7 compared to a rice paddie soil of 50+! This means that an aquasoil is going to hold 5x more nutrients than EcoComplete.
Agronomic characteristics identified in B1, C1, Z1, and NP2 acid volcanic rock powder samples.
But isn't EcoComplete packed full of nutrients too?
EcoComplete is volcanic basalt, essentially lava rock and unfortunately due to its lack of organic matter, does not develop humus. Volcanic basalt contains some micro and macro a single nutrients. The professors of Environmental Nanotechnology, Monitoring & Management were able to extract the nutrients using citric acid trying to mimic natural conditions. They stated, "The availability of some macronutrients and micronutrients were evaluated in conditions close to natural through nutrient extraction with citric acid solution diluted to 2%". The micro and macro nutrients they were able to extract were aluminum, calcium, magnesium, copper, iron, manganese, potassium, and zinc. Below is a chart of the available nutrients they extracted.
Nutrient content in B1, C1, NP2, and Z1 acid volcanic rock powder samples.
Something they observed that is an issue for aquarists is that volcanic basalt is "slow weathering and, therefore, the slow release of nutrients to the plants". So volcanic basalt has nutrients in it, but its not going to release this nutrients for a very long time which doesn't help root feeding plants in a planted aquarium. Furthermore, it composition is mostly micro nutrients with only one macro nutrient.
From what we've learned from LieBig's Law of the Minimum, our plants need both micro and macro nutrients in excess to make sure plants don't run out of anything. You can read more about LieBig's Law of the Minimum in out blog post, "Why do nutrient deficiency charts not work when addressing plant growth issues?".
So what does this all mean?
If you are going to have root feeding plants, an aquasoil as it will store 5x more nutrients than EcoCompelte. We know this because the CEC of EcoCompelte averages around 9.7, and the CEC of an aquasoil can be 50+. Furthermore, aquasoils develop a humus that helps store nutrients, lower nitrates and even detoxify heavy metals thus protecting your livestock. Do your plants a favor and use an aquasoils for your substrate. And most importantly, make sure you dose a liquid fertilizer, like Nilocg's Thrive All in One or the EI method, so that the aquasoil absorbs all that nutrients and provides it to your root feeding plants. Aquasoils have nutrients pack in them, but adding liquid fertilizer will make sure the aquasoil never runs out.
Are you looking for an all in one fertilizer? If so, check out Thrive. It's one of the best on the market and here is why.
Fundamentals of Soil Cation Exchange Capacity (CEC) - https://www.extension.purdue.edu/extmedia/ay/ay-238.html
Environmental Nanotechnology, Monitoring & Management - https://www.sciencedirect.com/science/article/pii/S221515321400004X
Rice Nutrient Management in California -
Diana Walstad - Ecology of a Planted Aquarium