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 |  | Hydroponics : HM Digital Meters Waterproof pH/Temperature Meter
 $119.95 |  |  |  | Hydroponics : Dutch Master DM Buffer pH 7.0, 500mL
 $13.50 |
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 |  | Hydroponics : General Hydroponics pH Down Dry 16 Pounds. Acid
 $64.98 |  |  |  | Hydroponics : Milwaukee Instruments Milwaukee pH Continuous Monitor with Cal Test
 $105.95 |
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 |  | Hydroponics : Milwaukee Instruments Milwaukee TDS Continuous Monitor with Cal-Test
 $105.95 |  |  |  | Hydroponics : Hanna Instruments Mini pH Controller
 $182.95 |
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 |  | Hydroponics : Milwaukee Instruments MA 850 Replacement probe for SM801/SM
 $99.95 |  |  |  | Hydroponics : Hanna Instruments GroChek EC Tester
 $112.95 |
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 |  | Hydroponics : Milwaukee Instruments Milwaukee pH - EC - TDS KIT
 $246.95 |  |  |  | Hydroponics : Dutch Master DM Buffer, 2.76Ms/Cm2
 $8.50 |
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 |  | Hydroponics : Green Air Products Inc. pH 4.01 Buffer, 16 Ounces
 $17.50 |  |  |  | Hydroponics : Green Air Products Inc. pH 7.01 Buffer, 16 Ounces
 $17.50 |
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 |  | Hydroponics : Milwaukee Instruments Milwaukee EC hand meter SM301
 $111.95 |  |  |  | Hydroponics : Milwaukee Instruments Milwaukee TDS hand held
 $111.95 |
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 |  | Hydroponics : Dutch Master DM Buffer pH 4.0, 500mL
 $13.50 |  |  |  | Hydroponics : Dutch Master DM Buffer 1400 Parts Per Million 500mL
 $13.50 |
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 |  | Hydroponics : HM Digital Meters TDS-3 Handheld TDS meter
 $44.95 |  |  |  | Hydroponics : Milwaukee Instruments Milwaukee TDS continuous read
 $118.95 |
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 |  | Hydroponics : Hanna Instruments Salinity (NaCI) Calibration solution 30g-l.
 $26.95 |  |  |  | Hydroponics : Nutradip (Tri Meter) Nutra-Dip continuous EC meter
 $104.95 |
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 |  | Hydroponics : Hanna Instruments GroChek TDS Tester
 $112.95 |  |  |  | Hydroponics : Milwaukee Instruments Milwaukee pH hand meter SM101
 $120.95 |
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 |  | Hydroponics : Botanicare Ph Adjuster Solutions Ph High, 1 Gallon
 $34.95 |  |  |  | Hydroponics : Oakton Oakton Calibration Solution 15,000 uS, case of 20
 $38.95 |
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 |  | Hydroponics : Hanna Instruments GroChek EC Electrode
 $56.95 |  |  |  | Hydroponics : Milwaukee Instruments Milwaukee EC continuous read
 $118.95 |
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 |  | Hydroponics : Oakton Oakton pHTestrs replacement sensor
 $90.95 |  |  |  | Hydroponics : Hanna Instruments pH Combo Electrode Glass Body - Refillable Temp. Sensor
 $172.95 |
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 |  | Hydroponics : Hanna Instruments 12880 S/cm Calibration Solution, 25 x 20mL, case of 25
 $33.95 |  |  |  | Hydroponics : Oakton Oakton Waterproof EC Tester 11+
 $143.95 |
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 |  | Hydroponics : Oakton Oakton Waterproof EC tester
 $108.95 |  |  |  | Hydroponics : Oakton Oakton waterproof Total Disolved Solids
 $92.95 |
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 |  | Hydroponics : Nutradip (Tri Meter) Nutra-Dip continuous pH meter
 $138.95 |  |  |  | Hydroponics : Hanna Instruments GroChek replacement probe for HI9813-0
 $119.95 |
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 |  | Hydroponics : Oakton Oakton pHTestr 20 - .01 pH Accuracy *ATC
 $133.95 |  |  |  | Hydroponics : Oakton Oakton Replaceable Electrodes pH WP 2 Pen
 $69.95 |
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 |  | Hydroponics : Hanna Instruments Replacement pH Electrode for HI98127, HI98128, HI98129, & HI98130
 $63.95 |  |  |  | Hydroponics : SpectraPure ( R.O. Filters) In Line Dual TDS Meter
 $54.95 |
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 |  | Hydroponics : Oakton Oakton Low/High/EC High Replacement Sensor
 $65.95 |  |  |  | Hydroponics : Hanna Instruments GroChek Hanna pH/EC/TDS/C/PPT Pocket Tester
 $202.95 |
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 |  | Hydroponics : General Hydroponics pH 7.0 Calibration Solution 8 Ounces
 $11.98 |  |  |  | Hydroponics : Active Air ActiveAir Soil Ph Tester
 $12.95 |
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 |  | Hydroponics : Batteries for pH/TDS pen, pack of 4
 $11.95 |  |  |  | Hydroponics : Hanna Instruments Combo pH/EC/TDS/C/PPM Tester
 $202.95 |
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 |  | Hydroponics : Hanna Instruments DiST 1 TDS Tester
 $76.95 |  |  |  | Hydroponics : Bluelab Bluelab pH Truncheon
 $184.95 |
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 |  | Hydroponics : Milwaukee Instruments PH7 Solution, 220ml
 $14.95 |  |  |  | Hydroponics : Hanna Instruments pH Electrode with 2 m (6.6') cable for HI981401N & HI981404N
 $63.95 |
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 |  | Hydroponics : Milwaukee Instruments Milwaukee Waterproof pH Tester
 $76.95 |  |  |  | Hydroponics : General Hydroponics pH Up 8 Ounces Base
 $12.98 |
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 |  | Hydroponics : Oakton Oakton Waterproof TDS Tester Low (0-1990 ppm / 1% FS)
 $101.95 |  |  |  | Hydroponics : Hanna Instruments pHep
 $67.95 |
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 |  | Hydroponics : Oakton Oakton pHTestr 10 - .1 pH Accuracy ATC*
 $123.95 |  |  |  | Hydroponics : Milwaukee Instruments Milwaukee TDS T75 Tester WP
 $78.95 |
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 |  | Hydroponics : Hanna Instruments 1382ppm Solution, 230ml
 $19.95 |  |  |  | Hydroponics : HM Digital Meters Waterproof EC/TDS/Temp Combo Meter
 $79.95 |
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 |  | Hydroponics : Milwaukee Instruments PH4 Solution, 220ml
 $14.95 |  |  |  | Hydroponics : Milwaukee Instruments Milwaukee Sugar Refractometer
 $116.95 |
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 |  | Hydroponics : Oakton Oakton pHTestr 30 - .01 pH Accuracy Temperature Display *ATC
 $152.95 |  |  |  | Hydroponics : Milwaukee Instruments Milwaukee TDS T76 Tester WP
 $78.95 |
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 |  | Hydroponics : General Hydroponics pH 4.01 Calibration Solution 8 Ounces
 $11.98 |  |  |  | Hydroponics : Hanna Instruments Hanna pHEP 4 Meter
 $114.95 |
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 |  | Hydroponics : Green Air Products Inc. pH 7.01 Buffer, 8 Ounces
 $13.75 |  |  |  | Hydroponics : Active Air ActiveAir 3 - Way Meter
 $14.95 |
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 |  | Hydroponics : Hanna Instruments Champ pH Tester
 $63.95 |  |  |  | Hydroponics : Hydrofarm Hydro RX Water & Soil
 $44.95 |
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 |  | Hydroponics : General Hydroponics pH Test Kit, 1 Ounce
 $11.98 |  |  |  | Hydroponics : Hanna Instruments 1413mS/cm Sol. 230mL
 $19.95 |
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 |  | Hydroponics : Oakton Oakton Replaceable Electrodes pH WP 1 Pen
 $55.95 |  |  |  | Hydroponics : Green Air Products Inc. pH 4.01 Buffer, 8 Ounces
 $13.75 |
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 |  | Hydroponics : Bluelab Bluelab Truncheon
 $140.00 |  |  |  | Hydroponics : Nutradip (Tri Meter) Probe pH Electrode
 $70.95 |
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 |  | Hydroponics : Active Air ActiveAir Moisture Meter
 $11.95 |  |  |  | Hydroponics : Oakton Oakton Waterproof EC Tester High (0-19.90 mS / 1% FS)
 $101.95 |
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 |  | Hydroponics : Milwaukee Instruments EC65 Waterproof Tester
 $81.95 |  |  |  | Hydroponics : Hanna Instruments GroChek replacement probe for HI9813
 $116.95 |
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 |  | Hydroponics : Oakton Oakton Waterproof TDS Tester High (0-10.00 ppt 1% FS)
 $101.95 |  |  |  | Hydroponics : General Hydroponics pH Down 8 Ounces Acid
 $12.98 |
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 |  | Hydroponics : General Hydroponics pH Test Indicator 8 Ounces
 $14.98 |  |  |  | Hydroponics : Hanna Instruments GroChek pH Tester
 $112.95 |
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 |  | Hydroponics : Milwaukee Instruments Milwaukee Double Junction pH Electrode w/ 1 meter cable
 $53.95 |  |  |  | Hydroponics : Oakton Oakton Waterproof EC Tester Low (0-1990)
 $101.95 |
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 |  | Hydroponics : Oakton Oakton Waterproof pH Tester Basic
 $93.95 |  |  |  | Hydroponics : Bluelab Commercial Truncheon
 $139.95 |
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 |  | Hydroponics : Hanna Instruments DiST 5 EC/TDS Meter
 $131.95 |  |  |  | Hydroponics : American Hydroponics Nutritest 2 Ounces Cal Sol 27.7 for Truncheon
 $9.95 |
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 |  | Hydroponics : Bluelab 4.0 250 ML Calibration Solution
 $15.00 |  |  |  | Hydroponics : Bluelab 7.0 250 ML Calibration Solution
 $15.00 |
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 |  | Hydroponics : Hanna Instruments 1500PPM Solution, 230ml
 $19.95 |  |  |  | Hydroponics : Milwaukee Instruments Milwaukee pH hand meter SM100
 $109.95 |
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 |  | Hydroponics : Cal Sol 1380 parts per million, 2 Ounces
 $10.98 |  |  |  | Hydroponics : Hydro-Logic DM-2 Industrial Dual TDS Monitor
 $80.00 |
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 |  | Hydroponics : Oakton Oakton Ultra Basic pH Tester
 $79.95 |  |  |  | Hydroponics : Hanna Instruments 1000ppm Calibration Solution
 $11.95 |
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 |  | Hydroponics : Oakton Oakton TDS Tester Ultra Basic
 $86.95 |  |  |  | Hydroponics : Oakton Oakton Waterproof TDS Tester11+
 $143.95 |
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 |  | Hydroponics : Hanna Instruments Gro'chek replacement probe for HI9813-6
 $127.95 |  |  |  | Hydroponics : Hanna Instruments Storage Solution, 16 Ounces
 $22.95 |
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 |  | Hydroponics : Oakton pH 4.01 Solution, case of 20
 $37.95 |  |  |  | Hydroponics : Hanna Instruments PH4 Calibration Solution, 16 Ounces
 $22.95 |
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 |  | Hydroponics : Hanna Instruments Electrode Cleaner 16 Ounces
 $23.95 |  |  |  | Hydroponics : Nutradip (Tri Meter) Nutra-Dip continuous TDS meter
 $104.95 |
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 |  | Hydroponics : Milwaukee Instruments PH7 Solution, 20ml, case of 25
 $26.95 |  |  |  | Hydroponics : Green Air Products Inc. Electrode Cleaner Twin Pack, 2x8 Ounces
 $22.50 |
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 |  | Hydroponics : Hanna Instruments 1382ppm TDS Sol, 460ml
 $21.95 |  |  |  | Hydroponics : Hanna Instruments PH7 Calibration Solution, 16 Ounces
 $22.95 |
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 |  | Hydroponics : Bluelab 4.0 500 ML Calibration Solution
 $23.00 |  |  |  | Hydroponics : Bluelab BlueLab Combo Meter
 $255.00 |
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 |  | Hydroponics : Hydrofarm Pro pH Up 1 Pint.
 $11.50 |  |  |  | Hydroponics : Hydrofarm Pro pH Down 1 Pint.
 $11.50 |
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 |  | Hydroponics : Hanna Instruments GroChek Hanna EC/TDS Monitor w/ HI7632 EC Probe
 $116.95 |  |  |  | Hydroponics : Hanna Instruments pH 7.01 Calibration Solution, 25 x 20mL, case of 25
 $35.95 |
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 |  | Hydroponics : Green Air Products Inc. 1413uS & 1500 PPM Calibration Kit, Twin Pack 2x8 Ounces.
 $22.50 |  |  |  | Hydroponics : Bluelab 7.0 500 ML Calibration Solution
 $23.00 |
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 |  | Hydroponics : Hanna Instruments GroChek EC/TDS Monitor
 $128.95 |  |  |  | Hydroponics : Hanna Instruments 1413 S/cm (EC) Calibration Solution, 25 x 20mL, case of 25
 $35.95 |
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 |  | Hydroponics : Milwaukee Instruments Milwaukee 3 function SM802
 $205.95 |  |  |  | Hydroponics : Milwaukee Instruments PH4 Solution, 20ml, case of 25
 $26.95 |
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 |  | Hydroponics : Hanna Instruments 1382 PPM@25C Calibration Solution, 25 x 20mL, case of 25
 $35.95 |  |  |  | Hydroponics : Hanna Instruments GroChek Hanna pH Indicator
 $116.95 |
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 |  | Hydroponics : Bluelab Nutrient Probe Cleaning Kit
 $25.00 |  |  |  | Hydroponics : Hanna Instruments pH 4.01 Calibration Solution, 25 x 20mL, case of 25
 $35.95 |
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 |  | Hydroponics : General Hydroponics pH Control Kit
 $20.98 |  |  |  | Hydroponics : Milwaukee Instruments 1382 TDS Solution, case of 25
 $26.95 |
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 |  | Hydroponics : Hanna Instruments 1500 PPM@25C Calibration Solution, 25 x 20mL, case of 25
 $35.95 |  |  |  | Hydroponics : Milwaukee Instruments 1500 ppm Packet, case of 25
 $26.95 |
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 |  | Hydroponics : Hanna Instruments GroChek pH/EC/TDS Meter
 $239.95 |  |  |  | Hydroponics : General Hydroponics pH Down Dry 1.5 Pounds. Acid
 $17.98 |
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 |  | Hydroponics : General Hydroponics pH Up Dry 1.5 Pounds. Base
 $17.98 |  |  |  | Hydroponics : Green Air Products Inc. pH Meter Maintenance (pH 4.01, pH 7.01, Electrode Storage Cleaner) Tri-Pack 3x8 Ounces
 $31.25 |
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 |  | Hydroponics : Milwaukee Instruments Milwaukee pH continuous read
 $118.95 |  |  |  | Hydroponics : Green Air Products Inc. Meter Maintenance (Cleaning & Storage Solutions) Tri-Pack
 $31.25 |
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 |  | Hydroponics : General Hydroponics pH Down 1 Gallon Acid
 $34.98 |  |  |  | Hydroponics : General Hydroponics pH Up Dry 16 Pounds. Base
 $64.98 |
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 |  | Hydroponics : Nutradip (Tri Meter) Nutra-Dip continuous Tri meter (pH, PPM & Temperature)
 $238.95 |  |  |  | Hydroponics : Hanna Instruments GroChek pH/EC/TDS/C Meter w/Cal-Check Feature
 $280.95 |
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 |  | Hydroponics : Nutradip (Tri Meter) Nutra-Dip continuous Tri meter (pH, EC & Temperature)
 $238.95 |  |  |  | Hydroponics : Hanna Instruments GroChek pH/EC/TDS/Temp. Combo
 $203.95 |
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 |  | Hydroponics : Hanna Instruments GroChek pH & TDS Combo Continuous Reading Meter
 $187.95 |  |  |  | Hydroponics : General Hydroponics pH 7.0 Calibration Solution 1 Quart.
 $29.98 |
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 |  | Hydroponics : General Hydroponics pH 4.01 Calibration Solution 1 Quart.
 $29.98 |  |  |  | Hydroponics : Hydrofarm Pro pH Down 1 Quart.
 $14.50 |
 |
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 |  | Hydroponics : Technaflora pH UP, 1 Liter
 $14.33 |  |  |  | Hydroponics : Green Air Products Inc. 1413uS & 1500 PPM Calibration Kit, Twin Pack 2x16 Ounces
 $30.00 |
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 |  | Hydroponics : Hydrofarm Pro pH Up 1 Quart.
 $14.50 |  |  |  | Hydroponics : General Hydroponics pH Down 1 Quart. Acid
 $17.98 |
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 |  | Hydroponics : Technaflora pH Down, 1 Liter
 $14.33 |  |  |  | Hydroponics : General Hydroponics pH Up 1 Quart. Base
 $17.98 |
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 |
 |  | Hydroponics : Bluelab pH Probe Cleaning & Calibration Kit
 |