New to hydroponics - I have an NFT channel setup for herbs. How often do I need to test and adjust pH? I've heard anything from twice a day to once a week.

The wide range of advice you've seen (twice a day to once a week) reflects real variation in system size, plant load, and water quality rather than anyone being wrong. Here's a practical framework for NFT herb growing.

The first two weeks: daily testing

When you're starting out, daily pH and EC checks are valuable - not because you necessarily need to adjust every day, but because you're learning your system's behavior. Note:

• What time of day drifts most (typically peaks at end of light cycle)
• How much your pH moves in 24 hours
• Whether drift is consistently upward (most common) or bidirectional

After two weeks you'll have enough data to know how frequently you actually need to intervene.

NFT-specific considerations

NFT systems have some characteristics that affect pH management compared to DWC:

Smaller reservoirs drift faster. If your reservoir holds 10 gallons and you have 20 plant sites, each plant has only 0.5 gallons of solution - uptake by roots shifts pH and EC significantly in a few hours. Larger DWC buckets (3–5 gallons per plant) buffer changes better.

Continuous flow means roots are never submerged. The thin nutrient film means pH changes at the root surface can be more extreme than reservoir readings suggest. This is why maintaining a stable reservoir pH matters more in NFT than in systems where roots sit in a large buffering volume.

Channel length matters. In long NFT channels, pH at the inlet and outlet can differ by 0.3–0.5 units. If possible, test from both ends when setting up.

A practical testing schedule

| System stage | Recommended frequency | |---|---| | First 2 weeks | Daily | | Weeks 3–4, plants establishing | Every 2 days | | Mature, stable system | Every 2–3 days | | Larger reservoir (15+ gal) or slow-growing herbs | Every 3–4 days |

When to test more frequently:

• Hot weather (ambient temps above 75°F accelerate drift)
• Adding new plants or changing nutrient solution
• After treating for any pest or disease
• If plants are showing any stress symptoms

Target pH range for herbs

For basil, cilantro, and mint in NFT: target 5.8–6.3. These herbs tolerate slightly acidic conditions well. Adjust when pH drifts outside 5.5–6.8; nutrient availability becomes impaired beyond those limits.

Equipment tip

A cheap digital pH pen (sub-$20) will drift in calibration faster than you'd like. Calibrate against fresh pH 4.0 and 7.0 buffer solution at least weekly. Spending $50–$70 on an Apera PC60 or BlueLab pen pays off in consistent, trustworthy readings.

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This answer is reviewed against published horticultural research. It is not a substitute for advice from a certified horticulturalist.