The SUBEX Experiment
Experiment Code: SUBEX-2025-05-01
An independent study comparing the performance of five commercial substrates in planted nano aquariums over a five-month period.
Download Full Report (PDF)Abstract
The choice of substrate is one of the most critical factors in establishing a successful planted aquarium, yet hobbyist decisions are often influenced more by marketing claims than by empirical evidence. This study systematically evaluated five widely used commercial substrates... The results revealed a distinct trade-off between vegetative and ecological performance. Seachem Flourite supported the most vigorous plant growth, while Fluval Stratum promoted a significantly richer micro-ecosystem. The findings indicate that no single substrate is universally superior; the optimal choice depends on the aquarist's specific goal.
Key Findings
- Plant Growth Winner: Seachem Flourite produced the most robust plant health, coloration, and overall biomass.
- Ecosystem Diversity Winner: Fluval Stratum cultivated the most complex and biologically diverse ecosystem, supporting a rich food web.
- Ecological Collapse: The DIY organic compost tank failed due to a breach in the sand cap, serving as a case study in the structural risks of soil-based systems.
- Unexpected Adaptation: In the nutrient-poor control tanks, the plant Cryptocoryne hudoroi developed the most extensive root system of the entire experiment as a survival mechanism to scavenge for nutrients.
Conclusion
For aquarium hobbyists, substrate selection should be guided by the system's primary objective. Based on the outcomes of this experiment, Seachem Flourite appears most suitable for aquariums focused on maximizing plant growth and visual health. In contrast, Fluval Stratum is better suited to those seeking to cultivate a biologically diverse ecosystem that supports shrimp, fry, and other sensitive fauna. This experiment reinforces that there is no single "best" substrate—only a best choice for a defined purpose.