Diquat Dibromide Reward Pondweed Aquaculture Tank
Diquat Dibromide (Reward) at Aquaculture and Aquatic-Weed Control Service — Bulk Tank Selection at Channel Catfish Pond Operations, Commercial Aquaculture Pond + Canal Aquatic-Weed Programs, Recreational Lake Management, and Hatchery Pre-Stocking Aquatic-Weed Control
Diquat dibromide (1,1'-ethylene-2,2'-bipyridyldiylium dibromide, CAS 85-00-7, marketed as Reward by Syngenta + Tribune + Diquat 2L generics) is the dominant U.S. aquatic-herbicide chemistry at pond + canal + lake aquatic-weed control. Diquat is a non-selective contact herbicide that disrupts photosynthesis at aquatic plant cell membranes via superoxide free-radical generation; treatment kills emergent + submerged + floating aquatic vegetation within 7-14 days at typical 0.5-2.0 mg/L diquat-cation use rate. Diquat is supplied as a 37.3% w/w (3.73 lb diquat-cation per gallon) brown aqueous concentrate at 2.5-gallon poly jug + 30-gallon HDPE drum + 270-gallon IBC tote + tank-truck commercial volume.
EPA-registered aquatic indications cover (1) pond + lake + canal aquatic-weed control at hydrilla + Eurasian watermilfoil + parrotfeather + curlyleaf pondweed + waterhyacinth + waterlettuce + duckweed + filamentous algae + emergent + submerged + floating macrophytes; (2) drainage + irrigation canal + ditch aquatic-weed control at agricultural + commercial-aquaculture infrastructure; (3) commercial-aquaculture pre-stocking + post-harvest pond aquatic-weed clearing at catfish + bait-fish + ornamental + recreational pond turnover; and (4) recreational lake management at public + private lake aquatic-weed problem areas. Diquat is NOT FDA-NADA approved at U.S. aquaculture as a fish-disease chemotherapeutant; its use at aquaculture facilities is governed by EPA FIFRA pesticide registration + state-pesticide-applicator-license framework rather than FDA-CVM aquaculture-drug regulation.
U.S. aquaculture diquat consumption is concentrated at U.S. channel catfish industry (Mississippi + Alabama + Arkansas + Louisiana farm-raised channel catfish industry pond-treatment + post-harvest pond-clearing), commercial aquaculture canal + irrigation system aquatic-weed control, recreational lake management programs (state lake-management + private + HOA + golf-course pond management), and hatchery + commercial-aquaculture pre-stocking aquatic-weed control. Storage envelope: diquat 37.3% concentrate is supplied at 2.5-gallon jug + 30-gallon drum + 270-gallon IBC tote + tank-truck delivery. Bulk-storage at HDPE atmospheric tank in the 250-2,500 gallon range serves commercial-aquaculture-supplier + larger-scale aquatic-weed-program facilities. Treatment-bath dose-tank at HDPE 100-2,500 gallon serves stock-tank + spreader-rig service at pond + canal application.
The eight sections below cite EPA FIFRA 40 CFR 152 + EPA NPDES 40 CFR 451 + 40 CFR 122 + EPA Clean Water Act aquatic-life criteria + EPA Worker Protection Standard 40 CFR 170 + state pesticide applicator + commercial-applicator license + OSHA HazCom + ACGIH TLV (0.5 mg/m3 diquat inhalation) + DOT UN2783 Class 6.1 toxic + ASTM D6692 + D6754 + operating practice at North American aquaculture diquat aquatic-weed programs.
1. Material Compatibility Matrix
Diquat dibromide 37.3% concentrate is mildly acidic (pH 6-8) + non-aggressive to standard polymers + metals at storage. Diquat aqueous solution at 0.5-2.0 mg/L treatment dose is essentially neutral + dilute. Material compatibility is governed by long-term polymer-stability + cleanability + post-treatment cleanup.
| Material | Diquat 37.3% concentrate | Treatment 0.5-2.0 mg/L | Notes |
|---|---|---|---|
| HDPE rotomolded (FDA-grade per 21 CFR 177.1520) | A | A | Industry-standard at diquat 37.3% concentrate bulk + dose-tank service; HDPE is the dominant manufacturer-supplied container at jug + drum + IBC tote |
| XLPE rotomolded | A | A | Equivalent to HDPE; standard at concentrate + dose service |
| Polypropylene (PP) | A | A | Acceptable at fittings + valves + small dose-tank service |
| PVDF (Kynar) | A | A | Premium dosing-pump tubing + diaphragm + valve seat |
| PVC Sch 80 | A | A | Standard at piping; full envelope |
| CPVC Sch 80 | A | A | Acceptable at piping; preferred at warmer water service |
| FRP (vinyl ester) | A | A | Acceptable at large bulk-storage; secondary alternative to HDPE |
| EPDM | A | A | Standard at gasket + flexible hose at diquat envelope |
| Viton (FKM) | A | A | Premium gasket service; full envelope |
| Buna-N (Nitrile) | A | A | Acceptable at full envelope |
| 304L stainless steel | A | A | Acceptable at fittings + valves; full envelope |
| 316L stainless steel | A | A | Standard at sanitary plumbing + transfer service |
| Carbon steel (epoxy-lined) | B | A | Acceptable at non-fish-contact buffer; not preferred at sanitary service |
| Galvanized steel | C | B | Acceptable at piping + fitting; not preferred long-term at concentrated |
| Aluminum | C | B | Acceptable at limited service; not preferred at concentrated bulk |
The dominant industrial pattern at North American aquaculture diquat programs is HDPE rotomolded stock-solution tank + dose-tank + spreader-rig + tank-truck delivery + IBC tote + drum at the 250-2,500 gallon range with PVC + CPVC + EPDM + Viton wetted plumbing + diaphragm or peristaltic dosing pump + boat or tractor-mounted spreader-rig. OneSource Plastics' 5-brand HDPE network (Norwesco, Snyder Industries, Chem-Tainer, Enduraplas, Bushman) is the standard atmospheric storage platform.
2. Real-World Industrial Use Cases
U.S. Channel Catfish Industry Pond + Post-Harvest Aquatic-Weed Clearing. Mississippi + Alabama + Arkansas + Louisiana farm-raised channel catfish industry deploys diquat at pond aquatic-weed control + post-harvest pond-clearing prior to next-season-stocking + canal + irrigation infrastructure aquatic-weed maintenance. Earthen-pond catfish operations face perennial aquatic-weed pressure from filamentous algae + duckweed + watermilfoil + waterprimrose + emergent vegetation; diquat at 0.5-1.0 mg/L treatment dose at pond + canal application is industry-standard. Treatment delivery is via tractor-pulled spreader-rig + boat-mounted spreader-rig at the pond surface.
USFWS National Fish Hatchery + State Hatchery Pre-Stocking Pond Clearing. NFHS + state hatcheries deploy diquat at pre-stocking aquatic-weed clearing at outdoor production-pond + holding-pond + transport-acclimation-pond service prior to fingerling + smolt-stocking cycle. HDPE stock-solution + dose-tank at 100-500 gallon scale is standard at hatchery pond-management.
Recreational Lake Management Programs. State lake-management programs (CA Department of Boating and Waterways, FL FWC, MN DNR, WI DNR, MI DNR, NY DEC, plus 50-state networks) + private + HOA + golf-course pond management + water-treatment-utility-reservoir aquatic-weed maintenance deploy diquat at aquatic-weed control at hydrilla + Eurasian watermilfoil + parrotfeather + duckweed + filamentous algae + emergent + submerged + floating macrophytes. Public-recreational-water diquat applications require state-licensed commercial pesticide applicator + EPA-registered product + state-water-quality-permit compliance.
Commercial-Aquaculture Canal + Irrigation Aquatic-Weed Control. Commercial-aquaculture canal + irrigation infrastructure (Idaho Snake River aquifer commercial trout canal + raceway-supply canal; Mississippi + Alabama catfish canal + drainage; Louisiana shrimp + crayfish + alligator pond canal) deploys diquat at aquatic-weed control at infrastructure water-supply maintenance.
Bait-Fish + Minnow Pond Aquatic-Weed Control. Common carp + golden shiner + fathead minnow + baitfish operations at Arkansas + Mississippi + Minnesota + Wisconsin + Indiana baitfish industries deploy diquat at production-pond aquatic-weed clearing prior to stocking + post-harvest + maintenance applications. Bait-fish operations at multi-pond commercial farms maintain HDPE 250-1,000 gallon diquat stock-tank + tractor-rig spreader-system at the production-system.
Ornamental + Koi Pond + Recreational Pond Aquatic-Weed Control. Private + recreational + ornamental + koi pond aquatic-weed control at smaller-scale commercial pond-management service deploys diquat at 0.5-2.0 mg/L treatment-dose at HDPE 100-500 gallon dose-tank + spreader-rig service. Public aquariums (Georgia Aquarium, Monterey Bay Aquarium, Shedd Aquarium) generally do NOT deploy diquat at indoor + display systems due to species-tolerance + ornamental display constraint; diquat is an outdoor pond + canal product.
3. Regulatory Framework
EPA FIFRA Pesticide Registration. Diquat dibromide is EPA-registered as an aquatic herbicide + pesticide under 40 CFR 152 + FIFRA framework. Primary EPA-registered products include Reward (Syngenta), Tribune (UPL), Diquat 2L generics (multiple), Weedtrine-D + related branded formulations. EPA registration includes label claims + use-pattern + species-tolerance + state-registration requirements. State pesticide regulators maintain state-specific registration + applicator-license + use-pattern restrictions.
EPA Worker Protection Standard 40 CFR 170. Diquat is a Restricted Use Pesticide (RUP) requiring certified applicator + state-pesticide-applicator-license at EPA + state-level + commercial-aquaculture-facility-applicator certification + Worker Protection Standard 40 CFR 170 personal-protective-equipment + re-entry-interval + pesticide-handler-training compliance.
FDA Aquaculture Drug Status. Diquat is NOT FDA-NADA approved at U.S. aquaculture as a fish-disease chemotherapeutant. Aquaculture use is governed by EPA FIFRA pesticide registration framework rather than FDA-CVM aquaculture-drug regulation. Fish must NOT be harvested from diquat-treated water for human consumption within the EPA-label-specified post-application-restriction-interval (typically 14 days for fish-consumption from diquat-treated water; specific intervals depend on product label).
EPA NPDES Aquaculture Discharge. Aquaculture facility wastewater discharge per 40 CFR 451 + 40 CFR 122 NPDES applies; post-treatment diquat effluent must comply with permit-specific BOD + TSS + temperature + pH limits at receiving water. Diquat residual at receiving water is typically below detection due to rapid soil + sediment binding (diquat is strongly adsorbed to clay + sediment + organic matter with very limited water-phase migration). NPDES permit holders apply diquat under EPA Pesticide General Permit (PGP) or state-equivalent.
EPA Clean Water Act Aquatic-Life Criteria. Diquat is a Class 6.1 acute-toxic chemical with substantial fish-toxicity at concentrations greater than 5-15 mg/L (species-dependent); typical aquatic-weed-control treatment dose at 0.5-2.0 mg/L is below acute-fish-toxicity threshold but treatment-area dissolved-oxygen depression at decomposing aquatic-vegetation is the dominant fish-kill risk. Supplemental aeration is mandatory at full-pond aquatic-weed treatment.
OSHA HazCom + ACGIH TLV. Diquat is an OSHA HazCom-regulated acute-toxic + irritant; handling requires SDS-compliant PPE + HazCom training. ACGIH TLV-TWA for diquat is 0.5 mg/m3 inhalable; concentrated diquat dust + mist exposure should be controlled below ACGIH TLV. Diquat acute-ingestion toxicity is the primary occupational health concern (similar acute-toxicity profile to paraquat); ingestion + concentrated-spill-exposure requires emergency-medical-response.
U.S. DOT Hazardous Materials Transport. Diquat dibromide is regulated as UN2783 Organophosphorus Pesticide Solid N.O.S. Class 6.1 Toxic Packing Group III for transport; bulk + drum + IBC packaging must comply with 49 CFR DOT Hazmat regulations.
State Pesticide Applicator License + Certification. State pesticide regulators require certified-applicator license at commercial diquat aquatic-weed application; specific certification categories cover aquatic-pesticide + commercial-aquaculture + public-water-management applicator categories at state-specific test + continuing-education + record-keeping requirements.
4. Storage System Specification
Bulk Storage Tank. Diquat 37.3% w/w concentrate bulk storage at HDPE rotomolded 250-2,500 gallon scale: industrial HDPE resin per 21 CFR 177.1520; vertical conical-bottom or flat-bottom vessel; smooth-wall interior; 4-inch ANSI flanged top fill with closed-loop or pressure-vacuum vent; 2-inch flanged bottom outlet with PVC + CPVC ball valve; atmospheric vent with insect-screen + dust-cover; 16-inch top manway; sight glass or radar level transmitter; HDPE bulkhead fittings at all penetrations. Tank ratings 1.10-1.20 SG (diquat 37.3% concentrate specific gravity 1.18). Storage room is segregated from incompatible chemicals (no acid + base + oxidizer + flammable proximity per OSHA HazCom + EPA FIFRA storage requirements).
Concentrate Container Storage. Diquat 37.3% concentrate at original-manufacturer 2.5-gallon jug + 30-gallon drum + 270-gallon IBC tote storage at climate-controlled 50-100°F dry warehouse with secondary-containment at IBC + drum scale + restricted-access storage per EPA FIFRA Restricted Use Pesticide + Worker Protection Standard requirements.
Stock-Solution + Dose-Tank Buffer. 100-2,500 gallon HDPE atmospheric stock + dose-tank at commercial-aquaculture spreader-rig + tractor-mounted + boat-mounted dose-tank service receives metered diquat from bulk-tank or IBC tote + dilution water at calculated treatment-dose volume; treatment-bath delivery at the pond surface via boom-mounted spreader-rig nozzle + agitated-mix-tank discharge. Calibrated metering pump (LMI Milton Roy, Pulsafeeder, Grundfos, Iwaki Walchem) at 0.1-2 gal/hr concentrate delivery is integrated.
Hatchery + Canal Pre-Stocking Dose-Tank. 100-1,000 gallon HDPE atmospheric dose-tank at hatchery + canal + drainage-infrastructure aquatic-weed pre-stocking treatment service provides batch dose-preparation + metered application at the treatment area.
Secondary Containment. Bulk diquat storage requires 110% containment per state pesticide-storage + RCRA + facility plan; HDPE secondary-containment pan + concrete-bermed area with collection sump + curbed treatment-room flooring at 110% containment volume is standard. Containment surfaces must accommodate concentrated-pesticide spill cleanup + Worker Protection Standard re-entry compliance.
5. Field Handling Reality
Operator PPE. Diquat 37.3% concentrate handling requires P100 particulate respirator + organic-vapor cartridge respirator at concentrate + dose-tank operations, splash-resistant chemical goggles + face shield, butyl + Viton + Saranex chemical-resistant gloves (NOT latex; latex degrades + does not meet EPA Worker Protection Standard breakthrough resistance), Tyvek QC or Kappler chemical-resistant suit at concentrate handling, rubber boots, and supplied-air respirator at confined-space + concentrated-vapor exposure scenarios. Eye + skin + respiratory protection is mandatory at every concentrated handling cycle; diquat acute-ingestion toxicity establishes the worker-protection imperative.
Stock-Solution Preparation Procedure. Standard diquat stock + treatment dose preparation: charge dose-tank with 80% target volume of dechlorinated water, engage agitation, slowly meter measured diquat concentrate from bulk tank or IBC tote via dosing pump or graduated cylinder + funnel transfer (avoid splashing + foaming), top off with water to target volume, verify diquat concentration via UV-spectrophotometer absorbance at 310 nm or HPLC reference, and deploy to treatment pond or canal. Stock-solution preparation is conducted in dedicated treatment area with ventilation + emergency eye-wash + safety-shower fixed at the dose station + Worker Protection Standard re-entry compliance.
Treatment-Bath Dose Calculation. Treatment-bath dose calculation: target diquat concentration (0.5-2.0 mg/L cation) x raceway or pond treatment volume / concentrate strength (3.73 lb diquat-cation per gallon at 37.3% Reward concentrate) = required concentrate volume. Example: 1-acre pond at 4-foot average depth (1.3 million gallons) target 1.0 mg/L diquat-cation: 1,300,000 gal x 3.785 L/gal x 1.0 mg/L / 446,944 mg/L (3.73 lb/gal Reward) = ~11.0 gallons concentrate dose at full pond treatment.
Pond Treatment Delivery + Monitoring. Pond treatment delivery at catfish farm + recreational lake: tractor-pulled spreader-rig or boat-mounted spreader-rig dispatches stock-solution at calculated spread-rate around pond perimeter + grid-pattern; treatment is monitored via pre + post-treatment dissolved-oxygen + temperature + aquatic-weed visual observation through 7-14 day post-treatment cycle. Aquatic-weed die-off + decomposition + biological oxygen demand depression at treated pond is the critical post-treatment monitoring parameter; supplemental aeration is mandatory at full-pond treatment to prevent fish kill from oxygen depletion at mass aquatic-weed die-off.
Canal + Irrigation Treatment Delivery. Canal + irrigation aquatic-weed treatment: stock-solution metered into canal upstream of weed-area at calculated dose-rate continuously through 30-90 minute treatment window; downstream re-entry at treated water requires post-application-restriction-interval per EPA label + state-water-permit-restrictions.
Spill Response + Concentrate-Release Mitigation. Diquat concentrate spill response: evacuate non-PPE personnel, deploy supplied-air or organic-vapor-cartridge respirator + butyl + Viton chemical-resistant suit + boots + face shield, contain spill via absorbent (vermiculite + diatomaceous earth + clay-absorbent), neutralize residual via aggressive dilution with water, collect spill + absorbent at hazardous-waste-stream characterized at FIFRA + state RCRA pesticide-waste, and dispose at EPA-permitted hazardous-waste facility. Worker Protection Standard re-entry and emergency-medical-response procedures apply.
Tank Cleaning + Decontamination. HDPE bulk + stock + dose-tank cleaning between campaigns: drain to working level, fill with potable water + recirculate to dilute residual diquat, drain + verify residual diquat below detection via test-strip or HPLC, inspect interior, refill at next campaign. Triple-rinsing of empty diquat containers is mandatory per EPA + state pesticide-empty-container-disposal requirements. Confined-space entry per OSHA 29 CFR 1910.146 with respirator + atmospheric monitoring + Worker Protection Standard compliance at any internal inspection.
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