EcoSym

Welcome to EcoSym. The only state-of-the-art ecological simulator built for the home aquarium.

Aquariums are ecosystems, whether you have a low-tech planted tank where the ecosystem is the centerpiece or a high-tech fish-keeping setup where fish health is the main objective. How you design that ecosystem from day one determines the long term trajectory and maintenance needs of the tank.

Why simulate my aquarium?

For a new aquarist, running simulations rather than physical experiments can help you avoid costly resets or loss of livestock. Even a seasoned hobbyist can benefit from exploring how new combinations of species and conditions might interact. Depending on your setup, regular water changes might be largely optional or absolutely essential for keeping your creatures alive and healthy. Allowing floating plants to spread and completely cover your aquarium surface might be fine, or it might reduce gas exchange enough that your aquarium suffocates. Dosing ammonia while your tank establishes might help your cycle complete, or it might cause your cycle to stall indefinitely and leave your tank toxic.

The answers to all of these questions are dependent on a large set of interacting factors and common wisdom can be helpful for one tank and deadly for another depending on the specifics of your unique system. EcoSym can help you answer all of these questions and more by allowing you to describe your setup in detail and giving you results based on the underlying chemistry and biology, not rules of thumb that may or may not make sense for your specific setup.

About the model

EcoSym takes a first-principles approach to ecosystem modeling, tracking nutrients as they move between organic and inorganic pools based on chemical and biological processes and letting second order dynamics (growth, death, stability, succession) emerge as a result. The core fluxes are producers absorbing light and taking up nutrients from the water to grow, and bacteria decomposing organic matter to bring nutrients back into the dissolved pools that producers depend on. Together these two guilds form the foundation that everything else (grazers, predators, detritivores) ultimately rests on.

The model includes handling of advanced dynamics such as Droop kinetics for primary producer nutrient uptake, biofilm EPS (extracellular polymeric substances) matrix development providing shelter for benthic organisms, multi-stage anoxic biochemistry in deeper substrate, and macrophytic suppression of competing algae through allelopathy, among others. The simulation is fundamentally an ODE (ordinary differential equation) solver which takes all of this chemistry and biology into account and solves a system of equations for every biologically relevant element to predict how populations behave over time in a given setup.

How to simulate your aquarium

When you are ready to model your own tank, click 'New Simulation' to step through a setup which mirrors how you would actually create an aquarium:

1. Define the environment — tank volume, initial water chemistry, lighting, temperature, and substrate.
2. Choose your stocking — pick from the catalog of plants, animals, and microbes.
3. Define ongoing maintenance — optionally configure water changes, fertilizer dosing, plant trimming, etc.
4. Hit Run Simulation and watch your tank evolve! You will see a series of graphs describing how each species' biomass, the water chemistry, and the nutrient pools change over time along with a visual rendering of your tank and the species it contains.

After a run is complete, you will be able to download a CSV detailing the precise values tracked by the engine throughout the simulation. You will also be given the option to Duplicate your run to create a new simulation starting with the configuration values of the current one. Lastly, you can Compare to a similar run to make specific changes to your setup and watch side by side in real time how certain changes cause the trajectory of each tank to diverge.

EcoSym is a powerful modeling tool which takes parameter values from scientific literature when available. However, real-world aquariums have stochastic factors the model can't fully capture. These include which exact microbes hitchhiked in on your plants, the precise mineral profile of your water (unless you happen to know it!), and the complexities of animal behavior. For that reason, EcoSym does not claim to predict the exact timing and magnitude of certain events in your system. Rather it aims to produce realistic qualitative dynamics — such as the fact that your nitrogen cycle will or won't complete, or that certain species will or won't outcompete other species — with best-effort quantitative timing and magnitude.

Documentation

Simulation can help you figure out what will likely happen as a given system develops over time. Why that happens is the domain of active ecology and biology research. To help you get to know aquarium ecology at a deeper level and design more robust systems that achieve your vision for your own aquarium, EcoSym includes an extensive set of documentation describing the science handled by the model. Every process and behavior described in the documentation is programmed into the model, and research is cited when applicable. A Parameter Reference page is presented as an authoritative list of where constant values used by the model are derived from.

In the rest of the documentation you will find pages grouped by topic: Aquarium Ecology Overview for a high-level overview, dedicated sections for Producers, Consumers, and Microbes, and the Nutrient Cycling pages that follow each element through the system. Chemistry, Environment, and Death and Decomposition describe the abiotic processes, Food Web and Stability and Failure look at the ecosystem as a whole, and Species contains deep dives on the individual organisms in the catalog. A Glossary is available for unfamiliar terminology.