pH drift

Feed or run-off pH creeping outside 5.5–6.5. Slight drift inside the window is fine; outside it, uptake suffers and lockout follows.

Symptoms

• Feed or run-off pH outside 5.5–6.5.
• Reservoir pH climbing or falling between changes.
• Deficiency signs: low pH affects calcium and magnesium; high pH locks up iron, manganese and phosphorus.

Quick checks

• Calibrate your pH pen with fresh solution.
• Measure tap water pH and EC.
• Re-test after mixing all nutrients.

How to fix it

1. 1
   Check

   Calibrate first

   Calibrate your pen at least once a month and any time a reading looks odd. Store the probe in its storage solution.

2. 2
   Feed

   Mix in the right order and adjust pH last

   Adjust pH after all nutrients are added, a drop of pH Up or Down at a time, stirring and re-testing.

3. 3
   Environment

   Steady the reservoir

   In hydro, top up with plain pH-adjusted water and change the tank completely about once a week. Keep solution at about 18–21 °C.

4. 4
   Monitor

   Aim for the right half

   Hydro and coco: the lower half of 5.5–6.5. Soil: the upper half.

Likely causes

• Uncalibrated or worn pH pen.
• Hard UK tap water (common cause of high pH).
• Old solution in hydro, warm reservoirs and active root growth changing the pH.
• Adjusting pH before all nutrients are added.

What to avoid

• Don't chase tiny changes within the window: natural drift inside 5.5–6.5 is fine.
• Don't let the probe dry out.

Prevention

• Monthly calibration.
• Weekly reservoir changes in hydro.
• Weekly run-off checks in soil and coco.

When to get help

If pH swings hard within a day of mixing, check your meter against a second one, or email info@monkeynutrients.co.uk with your water readings.

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