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pH Buffer 4 Growth Technology 300 ml
pH Buffer 4 from Growth Technology is a precision calibration reference fixed at pH 4.01, providing the acid reference point essential for two-point pH meter calibration. Single-point calibration at pH 7 corrects offset but leaves slope error uncorrected — a gap that produces increasing measurement bias as pH moves away from neutral. This second reference point defines the electrode response slope, ensuring accurate readings across the 5.0 to 7.0 range where growers operate daily. The 300 ml bottle yields dozens of calibrations when dispensed into a separate clean container. Never return used buffer to the stock bottle. Order from plantandflower.be with fast delivery across Belgium.
pH Buffer 4 Growth Technology 300 ml – Acid Reference Point for Complete Calibration
If your pH meter only sees one calibration point, it only corrects one source of error. The pH Buffer 4 from Growth Technology provides the second reference at pH 4.01 that transforms a basic offset correction into a full two-point calibration. This acid reference defines the slope of your electrode's response curve — the parameter that determines measurement accuracy everywhere except pH 7. Combined with pH Buffer 7, it delivers the calibration precision that serious nutrient management demands.
Slope correction: what pH 4.01 actually calibrates
A glass pH electrode produces approximately 59.16 mV per pH unit at 25°C when new — the theoretical Nernst slope. As the membrane ages, this response diminishes. An electrode operating at 90 % slope reads pH 6.0 as 6.3 — a seemingly minor error that translates to measurably different nutrient availability at root level. By calibrating at pH 4.01, your meter quantifies the actual slope of your specific electrode at that moment and applies a real-time correction factor. The result: accurate readings throughout the 5.0 to 7.0 range regardless of electrode age. Without this second point, slope error accumulates silently, and every pH reading between measurements carries an invisible bias.
- Fixed pH 4.01 value: acid reference positioned at the lower boundary of the cultivation working range, optimising accuracy where it matters most.
- Slope definition: completes the two-point calibration by providing the second data point needed to calculate the electrode's actual mV/pH response.
- 300 ml bottle: provides dozens of calibration sessions with economical small-volume dispensing.
- Emergency storage use: can serve as temporary probe storage solution when KCl solution is unavailable, keeping the glass membrane hydrated.
Recognising electrode drift before it costs you
Electrode drift is invisible to the user during normal measurement. Your meter displays a number that appears stable and reasonable — there is no error indicator for gradual calibration loss. The first symptoms typically appear in the plants: unexplained deficiencies despite correct EC values, or increasing reliance on pH adjustment products. A thirty-second verification with pH Buffer 4 reveals the truth. Immerse your probe without entering calibration mode. If the reading deviates more than 0.2 units from 4.01, full two-point recalibration is needed. Schedule this check at minimum every two weeks during active cultivation. After probe replacement, extended storage or any meter anomaly, recalibrate immediately using both pH 7.01 and pH 4.01 references.
Storage and shelf life considerations
Buffer integrity is non-negotiable for calibration accuracy. Always dispense into a separate clean container — never dip the probe directly into the stock bottle. Discard used buffer immediately. Trace contaminants from your probe shift the solution's pH value, invalidating the reference for future use. Store the sealed bottle at room temperature away from direct sunlight and heat sources. Verify clarity before each use — discard any solution that appears cloudy or contains particulates. Complement your calibration routine with proper probe storage in KCl storage solution and periodic checks with a calibrated pH meter to maintain end-to-end measurement chain integrity.
Order pH Buffer 4 from plantandflower.be with fast shipping across Belgium. Complete your calibration toolkit with the acid reference point your meter needs.
Why is pH 4.01 chosen as the second calibration point?
pH 4.01 sits at the lower boundary of the working range for plant cultivation (typically 5.5 to 6.5). Calibrating at this point optimises slope correction accuracy precisely in the zone where measurement precision has the greatest impact on nutrient availability.
Can pH Buffer 4 be used to store my pH probe temporarily?
Yes, pH Buffer 4 can serve as emergency storage for a pH electrode when KCl storage solution is unavailable. The slightly acidic environment maintains membrane hydration. For long-term storage, dedicated KCl solution is preferable as it also replenishes the reference electrolyte.
How do I test my pH meter accuracy without recalibrating?
Immerse the probe in fresh pH Buffer 4 without entering calibration mode. If the reading deviates more than 0.2 units from 4.01, your electrode has drifted beyond acceptable limits and full two-point recalibration is required.
Do I always need both pH 7 and pH 4 for calibration?
For maximum accuracy across the full measurement range, yes. pH 7.01 corrects the offset and pH 4.01 corrects the slope. Using only one point leaves one error source uncorrected, which produces increasing bias as the measured pH moves away from the single calibration reference.
