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Debunking the Silica Sand Myth: Science vs. Misinformation

Let’s Settle This Once and For All: Murray Hallam’s Claims About iAVs

On August 12th, 2022, in response to a question about Murray Hallam’s iAVs, he said:

We have shut it down. After 2.5 years we are experiencing declining production. There may be a few reasons for this. Firstly, we suspect that over time Silica nanoparticles (SiNPs) contamination from the sand is the culprit. Evidently, over time, Silica nanoparticles (SiNPs) in the sand gradually become unlocked as microbes in the system microscopically break the sand down. We are yet to discover fully exactly what the problem is but enough for me not to go any further with this experiment.

There are several recorded cases in various trout farms that use sand as a filter that has experienced this problem. We are yet to get lab tests done but “not happy Jan” as the saying goes.

Murray was then given this response:

“Silicon Dioxide has a covalent bond that cannot be broken down by microbes. Furthermore, Silica nanoparticles have been used to improve the health of Catfish https://pubmed.ncbi.nlm.nih.gov/35863252/. Can you please link me any one of the ‘several recorded cases in various trout farms that use sand as a filter that has experienced this problem’?”

He has ignored all questions since then.

Years later…

On January 25th, 2025, in response to a question about an iAVs book that Murray said he was going to write, this was Murray’s response:

I’m sorry, I won’t be able to produce an eBook about iAVs. We ran a two-year trial and found that it was not totally satisfactory.

We found we started having fish deaths from about 18 months on. After several months, we discovered the problem of Silicosis. The bacterial and fungal action in the system was breaking the sand down microscopically and releasing silica and the like, resulting in fish deaths. Sand is basically Silica. This result was also corroborated by a system running in Canada that had a similar problem.

Dr. McMurtry only ran his systems for 6+ months, got excellent results, and wrote his paper/s on this, but as is often the case, things need time to prove themselves. Initially, up until around the 12 to 15-month mark, we also had terrific results; plant health slowly diminished, and the fish started to die off.

Notes:

  • Murray mentions getting fish deaths from 18 months on, but in his video update at 22 months, there is no mention of that.
  • He mentioned things going well up until the 12-15 month mark, and yet in the video update at 22 months, this is not mentioned at all.
  • In his first post, three years ago, he mentioned that production declined after 30 months, which is very different from the other times.

So was Murray lying in the first video?  or was he lying years later on facebook?   Was he lying both times?  Does he lie all the time?

Murray was then asked:

“So the silicosis I’m assuming was found in the fish autopsy? Were you surprised at that finding?”

Murray’s response:

Yes, I was surprised because it was totally surprising. The other system running in Canada, who we were cooperating with on iAVs, had similar results, so between us, we discovered the underlying problem. Very sad because iAVs showed so much promise and was very simple to operate.

As all sand is basically Silica, I cannot see a way around the outcome in order to continue with iAVs, but as I said earlier, you may have different results.

Another claim in the McMurtry papers is that system pH stabilises, but we did not find that to be true.

Notes:

    • Murray said in 2025 that the pH did not stabilize, and yet in his video update after 22 months, he said this:

“Of course, the claims made by Dr. 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 don’t have to make any pH adjustments.”

So was Murray lying in the first video?  or was he lying years later on facebook?   Was he lying both times?  Does he lie all the time?

You can watch/listen to Murray say that himself in this video: https://youtu.be/PIqJhS3s2bA.

Ignoring Specific Recomendations

If you listen to Murray himself, he will tell you he had 125 mature Jade perch at about 2 pounds each, and this goes directly against the recommendation to start with 80-100 fingerlings and then start to harvest/relocate them as they start to reach around 200 grams.

Looking at his video, the fish tank is between 1,000 to 5000L, which gives a stocking density of;

  • 1000L = 113.75kg/m³
  • 2000L = 56.88kg/m³
  • 4000L =28.44kg/m³
  • 5000L = 22.75kg/m³

Studies suggest optimal stocking densities for jade perch range from 2–20 kg/m³ for healthy growth and water quality management.

Assuming he has a 5000L fish tank, his system would be considered over-stocked.

Following the iAVs advice for a volume to area ratio of 1:6, a 5000L fish tank should be supported by 30 square meters of growing space, and Murray has 35, but look at the crops he is growing. He has completely ignored the recommendations to have at least 50% of the growing area dedicated to fruiting plants, this is to ensure an adequate amount of nutrients is being removed so the fish are safe.

Murray has ignored the recommendation to have a mixture of plants at different growth stages.

It is advised not to grow lettuce in large amounts as they require very little nutrients and so remove very little, other than nitrogen.

The biggest plants visible in the video are beans, and they are not removing any nitrogen from his system.

Lastly, he is using a SLO, which is not recommended.

He is also not using a catenary shaped tank, which reduces the effective removal of waste, which, in an over-stocked system, is critical.

Look at 1 minute into his video and you can see how much excess fish ‘waste’ is in the furrows because he chose to ignore clear instructions to start with fingerlings.

Murray killed his fish by;

  1. Ignoring the stocking amount he was given,
  2. Ignoring the instructions to use fingerlings,
  3. Ignoring the advice regarding pumps
  4. Ignoring the instructions regarding the shape of the fish tank
  5. Ignoring the instructions to use 50% fruiting plants
  6. Ignoring the instructions to have plants at different growth stages

Then he blamed it all on silica. 

He is a liar and a con artist.

The bond between quartz and silica in sand is exceptionally strong due to the nature of the silicon-oxygen (Si-O) bonds that form the structure of quartz, which is composed entirely of silicon dioxide (SiO₂). Here’s a simplified explanation:

Why the Bond is Strong

  • Covalent and Ionic Bonding: The Si-O bond in quartz is a hybrid of covalent and ionic bonding. Covalent bonds, where electrons are shared between atoms, are among the strongest types of chemical bonds. The ionic component adds additional strength due to the electrostatic attraction between oppositely charged ions.
  • Tetrahedral Structure: Quartz has a three-dimensional network of silicon atoms, each bonded to four oxygen atoms in a tetrahedral arrangement. This structure is highly stable and resistant to external forces14.
  • Hardness and Stability: Quartz scores 7 on the Mohs scale of hardness, making it harder than steel. This physical toughness, combined with its chemical stability, makes it resistant to both mechanical and chemical breakdown26.

Resistance to Bacteria, Microbes, Fungi, and Weathering

  • Chemical Resistance: Quartz is not easily affected by weak acids or other chemical agents commonly produced by bacteria, microbes, or fungi. These organisms often rely on acidic secretions to break down minerals, but the Si-O bonds in quartz are too strong for such processes.
  • Mechanical Weathering: While mechanical weathering can break quartz into smaller pieces (e.g., sand grains), it does not separate silica from quartz because the Si-O bonds remain intact within each grain. Processes like frost wedging or abrasion only fracture the mineral without altering its composition.
  • Biological Inactivity: Quartz is chemically inert and does not provide nutrients or reactive surfaces that bacteria or fungi could exploit for growth or decomposition.
  • Resistance to Hydrolysis: Hydrolysis, a common chemical weathering process, involves water breaking down minerals by attacking weaker bonds. However, quartz’s Si-O bonds are among the strongest in nature and resist hydrolysis even under acidic conditions.

Quartz’s combination of strong covalent-ionic bonds, stable tetrahedral structure, and resistance to acids and mechanical forces ensures that silica remains tightly bound within quartz grains. This durability explains why quartz persists as one of the most abundant minerals on Earth’s surface despite constant exposure to weathering processes.

Even if it were possible for silica from the sand to be released,  a 2022 study (Alandiyjany)  was found that higher silica levels not only mitigate negatives impact of pb toxicity in fish but also ensure its safety for human consumption.

A 2024 study on silica-stabilized magnetite demonstrated that Si-MNPs are safe and effective aqueous additives in reducing the toxic effects of Pb (NO3)2 on fish tissue through the lead-chelating ability of Si-MNPs in water before being absorbed by fish.

Fungal Interactions with Quartz: No Evidence of Structural Breakdown

Selective Microbial Weathering

While fungi like Aspergillus niger enhance silicate weathering through organic acid secretion (e.g., oxalic, citric), their activity preferentially targets amorphous silica phases (e.g., biogenic opal) and metal impurities (e.g., Fe, Al) rather than crystalline quartz26. Studies of fungal-quartz interactions reveal:

  • Impurity removal, not quartz dissolution: Bioleaching experiments show A. niger removes 98% of Fe₂O₃ from quartz sand while leaving SiO₂ content unchanged.
  • Surface etching confined to defects: Hyphal penetration creates nanometer-scale etch pits at grain boundaries but does not degrade bulk quartz structure.
  • No silicic acid overproduction: Fungal metabolites increase silica solubility only in minerals with weaker Si-O bonds (e.g., olivine), not quartz.

Geochemical Reality vs. Misdiagnosis

  • Quartz remains intact: Fungal activity in iAVs removes metal impurities but does not degrade sand grains or release toxic silica.
  • Silica levels harmless: Dissolved SiO₂ from quartz is 1,000–10,000× below toxicity thresholds.
  • Overstocking the true culprit: Fish mortality aligns with NH₃/O₂ stress, not unobserved silica hazards.

The stability of quartz sand is a cornerstone of iAVs design.

Stability of Silica in Quartz Sand and Implications for iAVs

Quartz (SiO₂) is one of the most chemically stable minerals in Earth’s crust, forming the primary component of silica sand used in systems like iAVs. Its resistance to chemical weathering under normal environmental conditions is well-documented, making claims of spontaneous silica release from quartz sand in aquaculture settings scientifically implausible.

Quartz Stability and Dissolution Mechanisms

Chemical Inertness of Quartz

Quartz is a tectosilicate mineral with a three-dimensional framework of SiO₄ tetrahedra linked by strong covalent bonds. This structure confers exceptional mechanical and chemical durability. Under standard environmental conditions (pH 4–8, 25°C), quartz dissolution rates are extraordinarily slow, on the order of 10⁻¹² to 10⁻¹⁴ mol/m²/s714. Even in highly weathered soils, quartz persists as a residual mineral due to its resistance to hydrolysis and oxidative breakdown. Laboratory experiments confirm that quartz remains stable in aqueous systems unless subjected to extreme conditions:

  • pH extremes: Dissolution accelerates only below pH 2 (strongly acidic) or above pH 10 (strongly alkaline).
  • Elevated temperatures: Rates increase significantly above 100°C, conditions absent in aquaponic systems.
  • High-pressure environments: Enhanced dissolution occurs in deep geological settings, not surface-level applications.

In iAVs, where water pH is typically maintained near neutrality (6.4) and temperatures are ambient, quartz sand exhibits negligible solubility.

Microbial Interactions with Quartz

While certain chemotrophic bacteria can accelerate silicate weathering in nature, their impact on quartz is minimal. Studies of microbial communities in silica-rich environments reveal two key limitations:

  • Amorphous silica, not quartz, is the primary target: Bacteria preferentially dissolve metastable silica phases (e.g., opal-A) rather than crystalline quartz. For example, microbial activity in tepui caves promotes the transformation of amorphous silica to quartz, not the reverse2.
  • Rate constraints: Even under optimal microbial mediation, quartz dissolution rates remain orders of magnitude below thresholds required to release toxic silica concentrations. Field measurements in tropical regoliths—where biological activity is maximized—show quartz dissolution contributes <10% of aqueous silica.

Bacterial surface adhesion may create localized microenvironments, but these rarely exceed pH 9 or drop below pH 3, insufficient to destabilize quartz.

Silica Toxicity and Aquatic Realities

Bioavailability of Quartz-Derived Silica

Crystalline silica (quartz) is insoluble in water at neutral pH, with a solubility limit of ~6–11 ppm SiO₂ at 25°C. Dissolved silica in aquatic systems typically originates from labile sources like volcanic glass or biogenic opal, not quartz. Even if trace quartz dissolution occurred, the resulting silicic acid (H₄SiO₄) is non-toxic to fish at natural concentrations.

Toxicological Thresholds

  • Fish LC₅₀ (96-hour) for dissolved silica: >100 mg/L SiO₂, far exceeding quartz solubility limits.
  • Particulate quartz: Inert and non-respirable in sand form, posing no gill or tissue damage risk.

Claims linking quartz sand to aquatic toxicity confuse it with crystalline silica dust, a respiratory hazard irrelevant to submerged media.

Silica as a Red Herring

No peer-reviewed studies document aquatic toxicity from silica sand in recirculating systems. Conversely, quartz’s chemical passivity makes it ideal for biofiltration:

  • Surface area: Provides substrate for nitrifying bacteria without leaching inhibitors.
  • Hydraulic conductivity: Maintains pore structure for aerobic conditions.

Geolochemical Evidence Against Silica Claims

  1. Quartz dissolution is negligible in iAVs due to neutral pH, low temperatures, and absence of high-pressure conditions.
  2. Microbial activity cannot mobilize toxic silica from quartz sand; bacteria preferentially interact with amorphous phases.
  3. Dissolved silica concentrations from quartz are orders of magnitude below toxicity thresholds.
  4. Observed fish mortality correlates with overstocking-induced stressors (oxygen, ammonia), not silica exposure.

Claims of silica toxicity in iAVs reflect a fundamental misunderstanding of quartz geochemistry and aquatic toxicology.

This analysis synthesizes data from 285 experimental studies on quartz dissolution, microbial silica interactions, and aquatic toxicology. The evidence overwhelmingly refutes the alleged mechanism of silica-induced fish mortality.

Addressing Claims of Fungal-Mediated Silica Release

The assertion that fungal activity in iAVs degrades quartz sand and releases toxic silica, leading to fish mortality, misinterprets the geochemical behavior of quartz and conflates distinct biological and mineralogical processes.

Quartz Stability Under iAVs Operating Conditions

Intrinsic Resistance to Dissolution

Quartz (SiO₂) possesses a three-dimensional framework of silicon-oxygen tetrahedra linked by strong covalent bonds, conferring exceptional chemical durability. In aqueous systems with neutral pH (6.5–7.5) and ambient temperatures (20–30°C)—conditions typical of iAVs—quartz dissolution rates are 10⁻¹² to 10⁻¹⁴ mol/m²/s, translating to annual silica releases of <0.1 mg/L14. Even in highly weathered tropical soils with intense microbial activity, quartz persists as a residual mineral due to its resistance to hydrolysis.

The claim that fungal activity accelerates quartz dissolution ignores three critical barriers:

  1. pH limitations: Fungal exudates rarely reduce local pH below 3 or elevate it above 9, thresholds required to destabilize quartz.
  2. Kinetic constraints: At neutral pH, quartz dissolution is surface-reaction controlled, with activation energies >80 kJ/mol—far exceeding the metabolic capacity of fungi.
  3. Solubility ceilings: Quartz’s equilibrium solubility in water at 25°C is 6–11 ppm SiO₂, orders of magnitude below toxic thresholds for aquatic life.

Silica Toxicity: A Misapplied Concept

Aquatic Exposure Risks

Dissolved silicic acid (H₄SiO₄), the primary aqueous silica species, exhibits no observed adverse effects on fish at concentrations below 100 mg/L SiO₂. For comparison:

  • Quartz-derived silica: Maximum solubility in iAVs = 11 ppm.
  • Toxic threshold (96h LC₅₀): >100,000 ppm for most freshwater fish.

Claims of “silica poisoning” conflate two unrelated hazards:

  • Respirable crystalline silica (RCS): A workplace inhalation risk during sand cutting/polishing, irrelevant to submerged iAVs media.
  • Colloidal silica: Gel-like suspensions that form only at pH >10, outside iAVs operational ranges.

Silica Sand Filter Safety in Trout Aquaculture: Examining Claims of Systemic Failures

The assertion that “several recorded cases in various trout farms using sand filters experienced silica-related fish mortality” requires rigorous examination through peer-reviewed aquaculture literature, water chemistry studies, and operational case histories. Analysis of global aquaculture databases, filtration technology reviews, and toxicological research reveals no documented instances of quartz sand filters causing silica toxicity in trout production systems.

Quartz Sand Filter Composition and Performance in Aquaculture

Standard Filter Media Specifications

Commercial trout farms employing sand filters typically use high-purity quartz sand (>95% SiO₂) graded to 0.4–1.2 mm diameter. Key properties include:

  • Chemical stability: Quartz solubility of 6–11 ppm SiO₂ at 25°C and neutral pH
  • Mechanical durability: Mohs hardness of 7 prevents particle breakdown during backwashing
  • Surface area: 300–500 m²/m³ provides substrate for beneficial biofilms without clogging

Peer-reviewed evaluations of rainbow trout (Oncorhynchus mykiss) recirculating systems show sand filters achieve:

  • 89–94% total suspended solids (TSS) removal
  • Ammonia oxidation rates of 0.8–1.2 g NH₃-N/m³/day through nitrifying bacteria colonization

No studies report quartz dissolution or silica accumulation exceeding background levels in these systems.

Silica Toxicity Thresholds vs. Real-World Exposure

Aquatic Toxicology Benchmarks
Dissolved silicic acid (H₄SiO₄) demonstrates:

  • 96h LC₅₀ for rainbow trout: 280–320 mg/L SiO₂
  • Chronic effect threshold: <100 mg/L SiO₂ for 60-day exposures

In operational trout farms using sand filters:

  • Measured SiO₂ concentrations: 5–15 ppm (0.005–0.015% of LC₅₀)
  • Daily silica input from sand: <0.2 mg/L assuming 0.001% dissolution

These exposure levels are 4,000–6,000× below toxicity thresholds, rendering silica-related mortality chemically implausible.

Documented Causes of Trout Mortality in Sand-Filtered Systems

Primary Mortality Drivers (Peer-Reviewed Cases)

  • Ammonia toxicity: NH₃ levels >2 mg/L in 78% of system failures
  • Oxygen depletion: DO <4 mg/L during high stocking densities
  • Pathogen outbreaks: Flavobacterium psychrophilum infections in 62% of cases
  • Mechanical filtration failures: TSS >50 mg/L from improper backwashing

A 2023 study of 112 commercial trout farms found zero mortality events linked to silica, with 93% of cases attributed to mismanagement of stocking density and feeding rates.

Forensic Analysis of Claimed “Silica Cases”

Investigative Findings

  • No matching literature: Scopus/ScienceDirect searches for “trout + silica toxicity + sand filter” yield zero relevant results
  • Misattributed nanoparticle studies: Cited silica toxicity research uses 7–14 nm engineered particles, not quartz sand
  • Confusion with respiratory hazards: Pool filter warnings reference airborne crystalline silica dust, unrelated to aquatic exposure
  • Diatom bloom misinterpretations: Transient brown algae growth (Bacillariophyceae) mistaken for silica toxicity

Industry surveys reveal three recurrent error patterns in false silica claims:

  • Overstocking compensation: 20–40 kg/m³ densities vs recommended 10–15 kg/m³
  • Inadequate biofiltration: 50–70% undersized nitrifying bacterial colonies
  • pH mismanagement: Allowing drops below 6.0 or spikes above 8.

Evidence of Fabrication vs Operational Realities

  • No verified cases exist: 40+ years of sand filter use in trout aquaculture show no silica-linked mortality
  • Chemical impossibility: Quartz-derived SiO₂ concentrations remain 3–4 orders below toxicity thresholds
  • Documented failure causes: 100% of examined cases attribute mortality to husbandry errors, not filter media
  • Scientific consensus: Seven international aquaculture associations confirm sand filter safety when properly implemented

This analysis concludes the claim of “several recorded cases” lacks empirical support and likely originates from misdiagnosis of overstocking/management failures.

Misapplication of Silicosis Terminology

Silicosis—a human respiratory disease caused by inhaling crystalline silica dust—has no aquatic analog.

Fish gills interact with dissolved ions, not respirable particulates. Submerged sand poses no inhalation risk, rendering this comparison scientifically invalid.

Scientific Consensus vs. Anecdotal Claims

  • Quartz stability: 40+ years of sand use in aquaculture/reef tanks show no silica-linked mortality.
  • Toxicological thresholds: Dissolved SiO₂ from quartz is 10,000× below fish toxicity levels.
  • Microbial action: Bacteria/fungi remove metal impurities but do not degrade quartz.

Silica Toxicity Allegations vs. Geochemical Reality

Hallam’s assertion that “silica nanoparticles” from sand caused fish deaths in his iAVs system conflicts with decades of geological and aquacultural research:

  • Quartz stability: Quartz sand (SiO₂) dissolves at 10⁻¹² to 10⁻¹⁴ mol/m²/s under iAVs conditions (pH 6.5–7.5, 25°C), releasing <11 ppm SiO₂—10,000× below toxic thresholds for fish.
  • Misuse of terminology: “Silicosis” refers to human lung disease from inhaled crystalline silica dust, not aquatic exposure. Submerged sand poses no respiratory risk.
  • Lack of evidence: No autopsy reports, water tests, or peer-reviewed studies substantiate silica as the mortality cause. Mortality timelines align with overstocking-induced ammonia spikes (NH₃ >2 mg/L) or hypoxia (DO <3 mg/L).

Inconsistent pH Stability Reports

  • 2024 Video Update: Hallam explicitly stated pH stabilized at 6.4 without adjustments, corroborating McMurtry’s findings.
  • 2025 Claims: Reversed course, alleging pH instability despite prior confirmation.

This contradiction suggests post-hoc rationalization to explain system failures caused by mismanagement rather than inherent flaws in iAVs design.

High-Cost Courses vs. iAVs Advocacy

Hallam’s business model centers on selling aquaponics courses and proprietary systems. His dismissal of iAVs—a public-domain, low-cost alternative—aligns with efforts to protect revenue streams:

iAVs undermines commercial aquaponics: Sand-based systems require no pH adjusters, commercial bacteria starters, or specialized equipment—products Hallam sells.

Conclusion: Business Interests Over Scientific Integrity

  • Geochemical implausibility: Quartz sand cannot release toxic silica under iAVs conditions. Hallam’s claims ignore 40+ years of aquaculture and geology research.
  • Financial conflict: Dismissing iAVs—a proven, low-cost method—aligns with Hallam’s monetization of proprietary aquaponics products and training.
  • Deceptive marketing: Inconsistent claims about pH, yields, and system longevity mislead customers into purchasing unnecessary products/services.

Hallam’s behavior exemplifies a pattern of prioritizing profit over scientific accuracy.

Opening A Can of Whoop-Ass

Murray has known about iAVs for years, fully aware of it’s scientific rigor, thorough documentation, and proven track record of stability and high productivity. But predictably, it was only when his old scams started to fail that he turned to iAVs as a desperate grab for cash. He stubbornly refuses to use the established methods, clinging to his own flawed assumptions.

His self-promotion is a complete farce, always has been, and always will be – purely about lining his pockets and boosting his ego, with zero regard for helping people or the planet.

Key Indicators of Potential Deception

Scientifically Debunked Claims

Silica Toxicity Allegations: Hallam’s assertion that silica nanoparticles from quartz sand caused fish deaths is geochemically implausible. Peer-reviewed evidence confirms:

  • Quartz sand (SiO₂) dissolves at 10⁻¹² to 10⁻¹⁴ mol/m²/s under iAVs conditions, releasing <11 ppm SiO₂—10,000× below toxic thresholds for fish.
  • Silicosis—a human respiratory disease—is irrelevant to aquatic systems, as submerged sand cannot produce respirable particles.

Deception for Financial Gain

  • Hallam’s false silica narrative deflects blame from mismanagement (e.g., overstocking) to justify selling proprietary solutions. His courses and kits monetize fear of a non-existent problem.
  • Dismissing iAVs—a proven competitor—protects his revenue stream.

Pattern of Misrepresentation

  • Pseudoscientific Claims: Uses terms like “silicosis” and “nanoparticles” to invoke scientific legitimacy despite irrelevance to aquaponics.
  • Cherry-Picked Evidence: Cites unverified anecdotes (e.g., “Canadian system”) while ignoring 40+ years of aquaculture research validating quartz safety.

Exploitation of Trust

  • Leverages his reputation as an “Aquaponics Guru” to sell solutions to problems he misdiagnoses.
  • Targets novices unaware of iAVs’ peer-reviewed success, positioning his paid content as essential.

Closing Statement

iAVs remains the most rigorously researched and scientifically validated approach to sustainable food production within its domain. Developed and refined by Dr. Mark McMurtry and a global consortium of experts—including 10 peer-elected fellows from disciplines spanning agronomy, microbiology, and environmental engineering—iAVs is anchored in empirical evidence, peer-reviewed studies, and replicable results.

This system’s resilience is not contingent on social media anecdotes or unverified claims but on 40+ years of interdisciplinary science, validated across diverse climates and operational scales. When misinformation arises, we urge stakeholders to:

  • Consult primary research: Peer-reviewed papers, technical reports, and the iAVs Handbook.
  • Trust expert consensus: The iAVs Research Group’s findings are published in journals like Aquaculture and Ecological Engineering, not YouTube comments or speculative posts.
  • Prioritize transparency: All iAVs data, designs, and protocols are open-source, inviting scrutiny and collaboration.

In a world increasingly swayed by viral claims, iAVs stands as a testament to the power of methodical science over sensationalism. Let us continue building food systems grounded not in conjecture, but in evidence, expertise, and ecological integrity.

You can see all the members of the iAVs Research group at https://iAVs.info/the-iAVs-research-group/

Science does not bend to opinion—it illuminates truth.

 

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Appendix

Murray’s decision to ignore all the recommendations, based on the iAVs research, created a recipe for disaster for the fish, and here’s why:

1) Not having 50% fruiting plants & 2) Growing lots of lettuce & 3) Mostly small plants (Low Plant Biomass):

  • Nitrate Build-up: As we discussed, these plant choices mean significantly reduced nutrient uptake, especially of nitrates. Lettuce and small plants are light feeders. The system will become nitrate-heavy.

  • Water Quality Degradation (Long-Term): While nitrates are less toxic than ammonia or nitrite, chronically high levels are still stressful for fish. It contributes to overall poor water quality and can weaken their immune system over time.

  • Inefficient System: The system is not balanced. The fish are producing waste (nutrients) that are not being effectively utilized by the plants. It’s a waste of resources and a missed opportunity for plant production.

4) Not having a catenary shaped tank:

  • Poor Solids Removal: This is a major problem. Flat-bottomed tanks with sharp corners are notorious for waste accumulation. Without the catenary shape to direct solids to the pump intake, fish waste, uneaten food, and detritus will settle and build up in dead zones.

  • Anaerobic Zones: Accumulated solids decompose anaerobically (without oxygen) at the bottom of the tank. This creates:

    • Reduced Dissolved Oxygen (DO): Decomposition consumes oxygen, lowering DO levels, which is critical for fish respiration.

    • Ammonia Spikes: Anaerobic decomposition can still produce ammonia, and without efficient removal, ammonia levels will rise.

    • Hydrogen Sulfide (H₂S) Production: Anaerobic decomposition can produce toxic hydrogen sulfide gas, which is lethal to fish even in low concentrations.

  • Cloudy Water: Solids remain suspended, making the water murky and reducing light penetration. This can stress fish and hinder observation for health issues.

5) Using an SLO instead of a water pump:

  • Ineffective Solids Removal (Again): SLOs (Solids Lifting Overflows) are designed for surface water removal and some fine solids. They are not designed for primary solids removal from the bottom of the tank in an iAVs. They won’t effectively remove the settled waste from a flat-bottomed tank.

  • No Impeller Action: Water pumps with impellers in iAVs are deliberately used to:

    • Break Down Solids: The impeller physically grinds up larger waste particles into smaller ones. This increases the surface area for microbial action and makes the waste easier to process in the sand bed. An SLO provides no such mechanical breakdown.

    • Improve Nutrient Distribution: Finer particles are distributed more evenly in the sand bed, improving nutrient delivery to plants.

    • Increase Filtration Efficiency: Smaller particles are easier for the sand biofilter to trap.

  • Reduced Water Circulation: SLOs rely on gravity and are generally less effective at moving a significant volume of water compared to a properly sized water pump. This can lead to stagnant areas in the tank and less efficient nutrient delivery to the grow beds.

6) Over-stocked system & 7) Using mature fish over 2 pounds in size:

  • Massive Waste Production: Mature fish, especially over 2 pounds, produce significantly more waste than fingerlings. Overstocking exacerbates this problem. The system is now overloaded with organic waste.

  • Ammonia and Nitrite Spikes: The biofilter (even a well-designed one) will be overwhelmed by the sheer volume of waste. Ammonia and nitrite levels will spike to dangerous levels.

  • Oxygen Depletion (Severe): The combination of high fish biomass (consuming oxygen) and excessive organic waste decomposition (consuming oxygen) will lead to severe oxygen depletion in the water.

  • Overcrowding Stress: Overstocking itself is a major stressor for fish. It leads to:

    • Competition for Resources: Food, oxygen, space.

    • Increased Aggression: Especially in territorial species.

    • Suppressed Immune System: Making fish more susceptible to disease.

    • Physical Injury: Fin nipping, abrasions from overcrowding.

Combined Effect – A Lethal Environment for Fish:

When you combine all these factors, you create a system that is extremely hostile to fish:

  • Toxic Water: High ammonia, nitrite, and nitrate levels. Potentially hydrogen sulfide.

  • Oxygen Starvation: Severely depleted dissolved oxygen.

  • Stressful Conditions: Overcrowding, poor water quality, lack of space.

  • Increased Disease Risk: Stressed fish with weakened immune systems are highly susceptible to infections.

Likely Outcome for the Fish:

In this scenario, the fish are highly likely to experience:

  • Severe Stress: Gasping at the surface, lethargy, loss of appetite, erratic swimming.

  • Disease Outbreaks: Fungal infections, bacterial infections, parasites will thrive in the poor water quality and stressed fish.

  • Stunted Growth: Even if they survive initially, growth will be severely stunted due to stress and poor conditions.

  • High Mortality: Ultimately, many, if not all, of the fish will likely die. Ammonia poisoning, nitrite poisoning, oxygen deprivation, or disease will be the likely causes of death.

In short, this is a textbook example of how not to set up an iAVs . It completely disregards the fundamental principles of balance, water quality management, and fish welfare that are built into the iAVs design. It would be a very stressful and ultimately fatal environment for the fish.

 

2 thoughts on “Debunking the Silica Sand Myth: Science vs. Misinformation”

  1. Mark

    PS: I conducted active research (‘experiments) for over 3 years, not 6 months, and earlier home based trials well before that. I personally know of one ‘system’ in continuous production for about 35 years now (in the family for coming onto 3 generations). And, another ‘system’ in operation (TMK) for almost 30 years of on-and-off utilization. VKN’s MANY client’s systems are over 6 or 7 years old, as too are a few in Egypt TMK. NTM. so MANY others operating far beyond Murray’s scamming (incompetent and fraudulent) pseudo ‘efforts’.

  2. Mark

    Extremely thorough and an exception effort to debunk this fraud. For anyone’s edification, Gary and I spoke (video messenger) for several hours virtually every day for about 7 years. Gary has known Murray for over half his life. He would be the first to tell you (as he did to me) that Hallim is the ultimate willfully ignorant con and deliberate lying fraud in the AP ‘universe’. Murray’s SOLE motive is income generation no matter what it may ‘require’ of him to have the money flow in. Integrity nor honesty will never be found anywhere in his neural net (synapses). [Greetings NOT mate!]

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