The Future Here: Self-Regulating pH

In traditional aquaponic systems, maintaining the correct pH balance is a constant struggle. Nitrification and other biological processes cause pH to decline, requiring frequent testing and costly, labor-intensive adjustments with chemicals. This instability can harm fish, stunt plant growth, and hinder microbial activity. But there’s a better way…

PH plays a critical role in the health and productivity of fish, plants, and beneficial microorganisms. However, pH tends to decline over time due to nitrification (the conversion of ammonia into nitrate) and other biological processes. Managing this requires regular testing and adjustments using alkaline or acidic amendments, which can be labor-intensive and costly.

Failure to maintain proper pH levels can lead to nutrient deficiencies for plants, stress or mortality for fish, and inefficiencies in microbial activity. These challenges highlight the importance of systems like iAVs that naturally maintain pH balance.

One of the most remarkable features of the Integrated Aqua-Vegeculture System (iAVs) is its ability to maintain stable pH levels over extended periods without requiring constant monitoring or chemical adjustments.

This stability is not only a practical benefit but also a scientifically proven characteristic of the system, as demonstrated in multiple research studies conducted over decades. Below, we explore how iAVs achieves this pH stability and why it matters for sustainable food production.

Scientific research has consistently demonstrated that iAVs achieves stable pH levels through its unique design and operation. Here are key findings from various studies:

Long-Term Stability

In the study “Food Value, Water Use Efficiency and Economic Productivity of an Integrated Aquaculture-Olericulture System as Influenced by Component Ratio“, researchers monitored water pH over 363 days of continuous operation which demonstrated a stable, slightly acidic environment maintained over an extended period without significant intervention.

In “Performance of an Integrated Aquaculture-Olericulture System as Influenced by Component Ratio“, researchers noted that water pH stabilized at approximately 6.0 by week five. Once balanced, the system maintained stable pH levels without requiring further adjustments.

Buffering Through Plant Uptake

The same study highlighted that plant uptake of anions and cations contributed to buffering water pH naturally. When nitrogen assimilation by plants matched nitrogen input from fish waste, alkaline amendments were unnecessary. This balance between nutrient input and uptake creates conditions for natural pH stability.

Plants can “outcompete” nitrifying bacteria for ammonium (NH₄⁺), because ammonium is energetically easier for them to assimilate than nitrate. Since plants directly uptake a significant portion of the ammonium, there is less ammonia available for conversion to nitrate by nitrifying bacteria. The nitrification process releases protons (H⁺), which increase acidity and lower pH. With reduced nitrification in iAVs, less acid is produced, contributing to pH stability.

The uptake of ammonium by plant roots acidifies the rhizosphere by releasing protons (H⁺), while nitrate uptake alkalizes it by releasing bicarbonate or hydroxide ions. This dual uptake mechanism helps plants regulate their local pH environment, further contributing to overall pH stability.

The iAVs Research Group demonstrated the crucial role of plants in maintaining pH stability in iAVs. Without plant uptake of nitrogen, nitrifying bacteria dominate, leading to increased nitrification and the subsequent release of acid.

Role of Sand Biofilters

In “Mineral Content and Yield of Bush Bean, Cucumber, and Tomato Cultivated in Sand and Irrigated with Recirculating Aquaculture Water“, researchers observed that water pH remained below 7.0 throughout the experiment. The sand beds played a crucial role by facilitating nitrification while buffering acidification through microbial processes and organic matter decomposition.

Due to the balanced nitrogen dynamics and buffering capacity in iAVs, alkaline amendments (like lime or calcium oxide) are generally not necessary when nitrogen input rates from fish feed approximate nitrogen assimilation rates by the plants. This contrasts with traditional aquaponic systems that often require periodic additions of a base to stabilize pH due to the acidifying nature of nitrification.

If you are just hearing about iAVs and want to see what it is and how it works, here is a short video:

The proven stability of pH in iAVs offers numerous benefits:

• Reduced Maintenance: Unlike conventional aquaponics systems that require frequent testing and chemical adjustments, iAVs minimizes labor requirements.
• Cost Savings: By eliminating the need for alkaline or acidic amendments, practitioners save money on inputs.
• Improved System Health: Stable pH ensures optimal conditions for fish health, plant growth, and microbial activity.
• Sustainability: The self-regulating nature of iAVs reduces reliance on external interventions, making it ideal for resource-limited environments.

While theoretical models and scientific studies provide a foundation for understanding pH stability in iAVs, real-world examples offer compelling evidence of its effectiveness. Murray Hallam, a proponent of practical aquaponics, demonstrates this in his greenhouse setup in the video below. Hallam highlights that his iAVs system, after an initial stabilization period, maintains a consistent pH of approximately 6.4 without the need for manual adjustments. This stability is achieved despite the absence of added nutrients or pH buffers, relying solely on the natural processes within the system.

“Of course, the claims made by doctor Mark McMurtry almost 40 years ago now, that that system would remain stable once it settled down, as we’re finding to be absolutely true. Our pH is settled to about 6.4. We we don’t have to make any pH adjustments.“

Hallam emphasizes that the system has been running for an extended period, and the pH has remained remarkably consistent. This stability is particularly noteworthy given the inherent fluctuations that normally occurs in aquaponic systems.

Hallam’s experience provides a valuable real-world example of the potential for pH stability in iAVs. This practical evidence complements scientific findings, reinforcing the notion that iAVs can offer a more stable and self-regulating environment for plant growth compared to traditional aquaponic systems.

Scientific research has unequivocally demonstrated that iAVs maintains stable pH levels through its integrated design and natural biological processes. Whether through plant nutrient uptake, microbial activity in sand beds, or balanced system ratios, iAVs creates an ecosystem where water chemistry remains consistent with minimal intervention. For those seeking sustainable food production methods that reduce labor, costs, and risks associated with fluctuating water parameters, iAVs provides a proven solution backed by decades of research.

In essence, the pH stability in iAVs is a result of a system design that prioritizes plant nutrient uptake, leading to reduced nitrification and enhanced natural buffering processes, primarily driven by the interaction between plant roots and the surrounding environment

This stability is yet another example of how iAVs stands apart as an efficient and resilient approach to aquaponics—offering practical benefits while aligning closely with ecological principles.