AWQI Study: pH Is the Least Stable Reading Week-to-Week

The AquaDoc Water Quality Index (AWQI)
Data powered by anonymized SmartSplash water chemistry readings.

Study Summary

  • Key finding: When pH was in range, it stayed in range within 7 days only 47.7% of the time.
  • Comparison: Total alkalinity stayed in range 78.9% of the time, and sanitizer stayed in range 71.0% of the time.
  • Sample size: n = 9,942 consecutive test pairs within 7 days.
  • What it means: Even after you get pH where you want it, it commonly moves again quickly, so regular checks matter.

Dataset

  • Coverage: 16,313 water tests across 1,502 customers
  • Date range: 2025-01-01 to 2026-02-20
  • Source: SmartSplash water chemistry readings (anonymized)

Method

We analyzed consecutive test pairs that occurred within 7 days. For each parameter, we first filtered to cases where the initial reading was in range, then measured how often the next test was still in range.

  • pH in range: 7.2 to 7.8
  • Total alkalinity in range: 70 to 150 ppm
  • Sanitizer in range: chlorine systems (free chlorine 1 to 6 ppm) and bromine systems (bromine 3 to 8 ppm)

Results

Metric Stayed In Range Within 7 Days Sample (n)
pH 47.7% 9,942 follow-up pairs
Total Alkalinity 78.9% 9,942 follow-up pairs
Sanitizer 71.0% 9,942 follow-up pairs

What This Suggests (and What It Does Not)

Suggests: pH is the fastest-moving core reading in typical week-to-week maintenance. If water feels like it is always "almost there," pH volatility is often part of the reason.

Does not prove: this does not prove a single cause of pH movement. Many real-world factors can influence pH between tests, including aeration, bather load, refill water, weather, and product dosing behavior.

Limitations

  • Observational dataset from real testing behavior, not a controlled experiment.
  • We did not standardize treatment steps taken between tests.
  • Some users test more frequently than others, and that can influence the mix of follow-up pairs.

How to Cite This Study

AquaDoc Water Quality Index (AWQI). “AWQI Study: pH Is the Least Stable Reading Week-to-Week.” Data powered by anonymized SmartSplash water chemistry readings. Dataset coverage: 16,313 tests (2025-01-01 to 2026-02-20).

FAQ

Does this mean alkalinity matters less than pH?
No. This suggests alkalinity is typically steadier week-to-week, and that steadiness often helps make the rest of water balance easier to manage.

How often should I re-check pH?
If your water tends to drift, weekly checks are a practical baseline. More frequent checks can help when you are actively making adjustments.

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