AWQI Study: Spas Drift Out of Range Faster Than Pools

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 51.1% of the time for pools vs 43.4% for spas.
  • Sanitizer drift: Sanitizer stayed in range within 7 days 74.0% of the time for pools vs 68.4% for spas.
  • What it means: Smaller water volume and typical spa usage patterns tend to show faster week-to-week chemistry movement.

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 tests that occurred within 7 days, then segmented results by pool vs spa. For each parameter, we filtered to cases where the initial reading was in range, and measured how often the next test was also in range.

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

Results

Metric Pools: Stayed In Range Within 7 Days Spas: Stayed In Range Within 7 Days
pH (if initially in range) 51.1% 43.4%
Sanitizer (if initially in range) 74.0% 68.4%

Interpretation

This pattern matches what many owners experience: spas can feel "harder to keep dialed in" because chemistry can change faster between checks. A practical takeaway is that a spa may benefit from a tighter testing cadence, especially during frequent use or after refills.

Limitations

  • Observational dataset from real testing behavior, not a controlled experiment.
  • We did not adjust for frequency of use, refill events, or dosing strategies between tests.
  • Segment sizes can differ, and results may vary by season and region.

How to Cite This Study

AquaDoc Water Quality Index (AWQI). “AWQI Study: Spas Drift Out of Range Faster Than Pools.” Data powered by anonymized SmartSplash water chemistry readings. Dataset coverage: 16,313 tests (2025-01-01 to 2026-02-20).

FAQ

Does this mean spas are unsafe or unmanageable?
No. It means spa chemistry often changes faster, so checking more regularly can help catch drift early and keep maintenance simple.

What should I prioritize in a spa?
Sanitizer and pH are the two most time-sensitive week-to-week readings in typical spa use, so those are good first checks.

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