pH Buffer 4.0 by Flairform — pH Meter Calibration Solution
FF-MTR-PH4-250
- Handpicked by growers
- Ships today
- Real advice, real people
- 5,000+ high yielding customers
- 30-day returns*
- Free shipping over $499*
- Low stock - 10 items left
Pairs well with
Flairform pH Buffer 4.0 is a calibration solution for pH meters, made to the internationally agreed recipe with NIST-specified ingredients. pH meters must be calibrated regularly to stay accurate — and professional practice calls for two buffers, not one. Paired with pH Buffer 7.0, this gives you a true 2-point calibration that confirms your electrode and meter are ranging correctly across the whole scale. Stabilised against algae growth for exceptional shelf life. Available in 250ml and 1L.
Specifications
- Always calibrate 2-point: pH 7.0 first, then 4.0. Single-point calibration on 7.0 alone can't confirm the slope — some meter brands claim it's enough, professional practice says otherwise.
- Never dip the probe into the bottle. Decant a small amount into a clean cup and discard it after use — dipping contaminates the whole bottle.
- Keep the bottle closed and stored cool and dark. Contaminated or degraded buffer means calibrating to a wrong reference.
How to Use
Pairs Well With
The other half of the 2-point calibration — always calibrate 7.0 first, then 4.0.
Flairform Electrode CleanerClean before you calibrate — a fouled probe upsets the slope either side of the buffer values.
Flairform pH UpOnce the meter reads true, adjust the reservoir with confidence — pH Up lifts solution that's drifted low.
Frequently Asked Questions
Do I need both pH Buffer 4.0 and 7.0?
Yes. It is essential to calibrate with at least two buffers differing by three or more pH units. Two-point calibration confirms the correct slope — that both the electrode and meter are ranging correctly. For nutrient solutions, 4.0 and 7.0 are the ideal pair.
My meter says calibrating with 7.0 only is fine — is it?
No, not by professional standards. Some manufacturers claim single-point 7.0 calibration is enough, but professional practice stipulates two buffers because one point can't verify the slope. A meter that reads 7.0 correctly can still be wrong at 5.8 — exactly where your nutrient solution sits.
Which buffer do I calibrate with first?
pH 7.0 first, then 4.0. The neutral point sets the offset, the second point sets the slope. Rinse the probe between buffers so you don't carry one into the other.
Can I store my pH probe in this buffer between uses?
No. pH buffers are not suitable for storing pH electrodes — they can upset electrode calibration. Use a dedicated storage solution like Flairform pH Electrode Storage instead.
Is this buffer hazardous?
No. Per the safety data sheet it is non-hazardous, non-corrosive and a non-dangerous good — a dilute potassium hydrogen phthalate solution requiring no PPE in normal use. Keep it out of waterways, as it promotes algae growth.
One Buffer Can't Confirm the Slope
Calibrate 2-point like the labs do. Free shipping over $499*.
Select Size
