Water Testing
Pool Reading Measurements
A practical reference for the readings PoolKit should capture, the units operators usually see, and the measurement methods that produce them.
PoolKit Position
Most chemistry readings are recorded in ppm, but not all of them. pH is unitless, ORP is recorded in mV, temperature is a temperature unit, and some problem-solving readings use ppb, psi, GPM, percent, pass/fail, or free-form notes.[4]
For PoolKit, the safer model is to store a reading value with its unit and measurement basis. A plain ppm value is not enough when the basis matters, such as ppm as CaCO3 for alkalinity or hardness, ppm as Cl2 for chlorine, and ppm as Br2 for bromine.[4]
Common Logbook Readings
These are the readings most likely to belong in the normal PoolKit logbook path.
| Reading | Typical unit | Common measurement methods | PoolKit note |
|---|---|---|---|
| Reading timestamp | Date and time | Operator entry, device clock, or controller export. | Required context for every record. |
| pH | pH, unitless | Phenol red color match, photometer, digital pH meter, or controller probe. | Do not label as ppm.[4] |
| Free chlorine (FCL or FC) | ppm or mg/L as Cl2 | DPD color test, FAS-DPD titration, test strip, photometer, or chlorine sensor. | Core chlorine sanitizer reading.[1][4] |
| Total chlorine (TCL or TC) | ppm or mg/L as Cl2 | DPD total chlorine test, photometer, or strip. | Needed to derive combined chlorine when FC is known.[4] |
| Combined chlorine (CC) | ppm or mg/L as Cl2 | Usually calculated as total chlorine minus free chlorine; some kits report it directly. | Store as measured or calculated with a clear source.[4] |
| Total bromine (TB) | ppm or mg/L as Br2 | DPD bromine color test, photometer, or strip. | Use instead of chlorine fields when the vessel is bromine-maintained.[2][4] |
| ORP | mV | ORP electrode from a controller or portable meter. | Record independently. It is not a direct ppm sanitizer conversion.[4] |
| Water temperature | deg F or deg C | Thermometer, heater sensor, automation system, or handheld meter. | Useful for comfort, spa checks, and saturation index calculations.[2][4] |
| Total alkalinity | ppm or mg/L as CaCO3 | Acid titration drop test, strip, or photometer. | Water balance input; basis should be preserved.[4] |
| Calcium hardness | ppm or mg/L as CaCO3 | Hardness titration, strip, or photometer. | Water balance input; not the same as total hardness unless the test says so.[4] |
| Cyanuric acid (CYA) | ppm or mg/L | Turbidity view-tube test, photometer, or strip. | Most relevant to stabilized chlorine pools.[3][4] |
| Salt or salinity | ppm, ppt, or g/L | Salt test strip, salinity meter, conductivity meter, or salt-chlorine generator controller. | Important for salt-chlorine systems; unit must be explicit.[4] |
| Total dissolved solids (TDS) | ppm or mg/L | Conductivity or TDS meter. | Broad water-balance signal, not an ingredient breakdown.[4] |
| Water clarity | Pass/fail, visibility note, or NTU | Visual main-drain visibility check or turbidity meter. | Keep flexible; many operators need a simple visibility status.[4] |
Situational Readings
These are useful when a property uses a relevant system, has a recurring issue, or needs a startup or troubleshooting report.[4]
| Reading | Typical unit | When it matters |
|---|---|---|
| Phosphates | ppb or ppm as PO4 | Algae and nutrient troubleshooting. |
| Nitrates | ppm or mg/L | Source-water or persistent algae investigation. |
| Copper | ppm or mg/L | Staining, source water, heaters, algaecides, or copper ionizers. |
| Iron | ppm or mg/L | Source-water staining and discoloration issues. |
| Silver | ppm or mg/L | Silver or copper-silver ionizer systems. |
| Borates | ppm or mg/L | Pools intentionally maintained with borates. |
| Monopersulfate (MPS) | ppm or mg/L | Non-chlorine oxidizer use; may matter because MPS can interfere with some sanitizer tests. |
| Ozone residual | ppm or mg/L | Ozone systems and safety checks; usually not a normal pool-water target. |
| Bacterial testing | Method-specific result | Regulatory, lab, remediation, or incident workflows rather than daily entry. |
Operational Readings
These are not chemistry readings, but they may belong near the logbook if PoolKit tracks daily equipment condition.[4]
Filter pressure
psi from a pressure gauge.
Flow rate
GPM from a flow meter or controller.
Pump state
On/off, schedule, speed, RPM, percent, or watts.
Chemical feeder output
Percent, dial setting, pump rate, or dose volume.
Implementation Stance
- Start with a small logbook set: pH, sanitizer residual, temperature, alkalinity, calcium hardness, CYA, TDS, salt, and optional ORP.
- Let vessel configuration choose the sanitizer panel: chlorine, bromine, and later other approved systems if needed.
- Store the unit and basis alongside each numeric reading.
- Do not convert ORP to sanitizer ppm; capture both when both are available.
- Keep problem-solving readings out of the default path until a report type, property setting, or future workflow asks for them.
References
- CDC. Guidelines for Keeping Your Pool Safe and Healthy. Used here for the position that disinfectant residual and pH are core pool checks.
- CDC. What You Can Do to Stay Healthy in Hot Tubs. Used here for hot tub sanitizer, pH, and temperature context.
- CDC. About The MAHC Current Edition. Used here to identify the current MAHC edition and cyanuric acid change notes.
- CDC. 2024 Model Aquatic Health Code, 5th Edition. Used here for testing methods, logbook candidates, ORP units, water clarity, equipment readings, and the broader candidate reading list.