What the log is for
A pool log does three jobs. It shows the health inspector your water was safe on the days nobody was watching. It warns you early, when pH has crept up three readings in a row. And it hands the pool over cleanly between whoever tests at 7 AM and whoever tests at 3 PM.
The ranges and test times on this page come from the CDC's Model Aquatic Health Code (MAHC), 5th edition, December 2024. It is a model code: states and cities adopt all of it, part of it or their own rules. Your local health code decides. Use this page as a well-sourced starting point and check it against the code that applies to your pool.
Downloads: the pool and spa log as a spreadsheet (XLSX), with tabs for the daily log, the weekly and monthly tests and the ranges, or the daily log as CSV. The page also prints clean, without menus or buttons.
The numbers at a glance
| What | Pool | Spa | How often | MAHC section |
|---|---|---|---|---|
| Free chlorine, minimum | 1.0 ppm, or 2.0 ppm if you use cyanuric acid | 3.0 ppm | Before opening, then every 2 h (manual feed) or 4 h (automated controller) | 5.7.3.1.1.2, 5.7.5 |
| Bromine, minimum | 3.0 ppm | 4.0 ppm | Same as chlorine | 5.7.3.1.2.2 |
| Bromine, maximum | 8.0 ppm while open | 8.0 ppm while open | At each test | 5.7.3.1.2.3 |
| Chlorine, maximum | As the product label says | As the product label says | At each test | 5.7.3.1.1.5 |
| pH | 7.0 to 7.8 | 7.0 to 7.8 | With every chlorine or bromine test | 5.7.3.4.1 |
| Combined chlorine | Act above 0.4 ppm | Act above 0.4 ppm | As your code requires | 5.7.4.4.2 |
| Water temperature | Record for heated pools | 104 °F (40 °C) maximum | With every chlorine or bromine test | 5.7.5.10, 5.7.4.7.2 |
| Total alkalinity | 60 to 180 ppm | 60 to 180 ppm | Weekly | 5.7.4.4.1, 5.7.5.5 |
| Calcium hardness | 2,500 ppm maximum | 2,500 ppm maximum | Monthly | 5.7.4.4.3, 5.7.5.6 |
| Cyanuric acid | 90 ppm maximum; closed at 300 ppm or more until fixed | Not used in new spas | Monthly, and 24 h after adding it | 5.7.3.1.3, 5.7.5.7 |
| Saturation index | Check | Check | Monthly | 5.7.5.8 |
| Total dissolved solids | Test | Test | Quarterly | 5.7.5.9 |
The CDC's shorter guidance for pool operators gives the same minimums (1 ppm free chlorine in pools, 3 ppm chlorine or 4 ppm bromine in hot tubs, pH 7.0 to 7.8) and says to test pH and disinfectant "at least twice per day (hourly when in heavy use)." Where a code adopts the MAHC, its 2-hour and 4-hour testing rules are the stricter ones to follow.
The daily log
One line per test. The first line is the test before opening. Write the reading as you see it, even when it is out of range, then write what you did and the retest. A log with only perfect numbers looks filled in after the fact.
| Time | Pool free chlorine | Pool pH | Pool clear (bottom visible) | Spa chlorine or bromine | Spa pH | Spa °F | Action and retest | Initials |
|---|---|---|---|---|---|---|---|---|
| 7:00 AM | 2.0 | 7.4 | Yes | 3.5 | 7.5 | 102 | None | MR |
A pool open from 7 AM to 9 PM with a manual feeder needs about eight tests a day under the 2-hour rule. With an automated controller it needs about four. If your pool and spa run on different systems, each follows its own interval. If the controller has an in-line ORP reading, the MAHC asks you to record it at the same time as each chlorine and pH test.
Before you open: the daily walk
The MAHC lists the checks to do before the pool opens each day (section 6.4.1.3.1). Here they are, shortened for a hotel pool. Tick them on the daily sheet.
- Deck, walkways and exits clear, clean and free of glass and debris.
- Drain covers, suction outlet covers and skimmer equalizer covers in place, secure and unbroken.
- Skimmer baskets, weirs, lids and suction outlets free of blockage.
- Inlet and return covers in place, secure and unbroken.
- Pump, filter, disinfection system, controller and probes running as they should.
- Water clear enough to see the bottom and anything on it.
- Underwater lights intact, with no exposed wires or water inside them.
- Safety signs in place and readable, and safety equipment where it belongs.
- Emergency phone or call system working, with the emergency numbers posted.
- Gates self-closing and self-latching, and no loungers left where a child could climb the fence.
- Chemical store and plant room doors locked.
- First aid kit stocked, and the cleanup kit for fecal, vomit or blood incidents in place.
- Slime and biofilm wiped from tile lines, steps and features.
If a drain cover is missing or broken, the pool does not open until it is fixed. That is the one item on this list a guest can be badly hurt by in seconds.
Weekly, monthly and twice a year
Weekly
- Test total alkalinity and log it.
- Include a deep end sample in the week's testing rotation.
- If you use stabilized chlorine as your main disinfectant, test cyanuric acid weekly.
- If you have a salt chlorine generator, test salt weekly or as its manufacturer says.
- Empty the pump basket, check the pressure gauge, and look and listen for leaks and noise at the pump.
Monthly
- Test calcium hardness and log it.
- Test cyanuric acid if you use it.
- Check the saturation index.
- Test every GFCI device around the pool and spa (MAHC 6.4.1.3.2).
- Backwash or clean the filter as its pressure and manufacturer require, and check the pressure is back to normal afterwards.
Every three and six months
- Quarterly: test total dissolved solids.
- Every 6 months: visually inspect the bonding conductors where you can reach them, and after any work that disturbed them.
When a reading is out of range
Write the reading down first. Then follow your written procedure and your chemical labels to correct it, retest, and write the retest on the same line. Never estimate a dose from memory, and never mix chemicals.
Some readings mean the pool closes now. The MAHC lists them as imminent health hazards that the health authority can close a pool for (section 6.6.3.1). Among them:
- Free chlorine or bromine below the minimum.
- Free chlorine above 10 ppm, or bromine above 8.0 ppm, while swimmers are in the water.
- pH below 6.5 or above 8.0.
- The bottom of the pool not visible.
- A broken, loose or missing main drain grate or suction outlet cover.
- Filtration or disinfection equipment not running.
- Cyanuric acid above 300 ppm while swimmers are in the water.
- Broken glass or sharp objects in the water or on the deck.
When you close, put up the closed sign, tell the front desk so guests hear it from you, and write down when it closed and when it reopened. For readings that are out of range but not on that list:
- pH out of range. Chlorine works poorly at high pH, and low pH is hard on swimmers and equipment. Correct it and retest before you trust the chlorine reading.
- Combined chlorine above 0.4 ppm. That is the strong chlorine smell guests mistake for too much chlorine. The MAHC asks the facility to act, for example with superchlorination or a water exchange.
- A fecal, vomit or blood incident. Clear the water and follow your contamination response plan and the CDC's guidance. The MAHC requires a written plan, so write it before you need it.
A reading that drifts out of range every afternoon is not bad luck. It is a feeder, a controller or a bather load problem, and it belongs on the engineering list.
Keeping the records
The MAHC says aquatic facility records should be kept for at least 3 years and be available to the health authority on request (section 6.4.1.2.1). Local laws can ask for more. Keep the daily sheets in one binder in the plant room, or scan them weekly. Whichever you choose, the inspector should be able to find any day in under a minute.
Store your test kit out of the sun, and replace reagents by their expiry date. A reading from an expired reagent is worse than no reading, because everyone trusts it.
Pool equipment in your maintenance plan
The chemical log keeps the water safe. The equipment behind it needs its own schedule: the pump, the filter, the heater, the controller and the GFCIs. Turndown's preventive maintenance library includes a weekly pool pump check (empty the basket, check the pressure gauge, look for leaks and listen for noise) and a monthly pool filter backwash that cannot be closed until the pressure is back to normal. Add your own plans for GFCI tests or the heater with their own required steps, and each one creates its job on time and lands in the equipment's history.
To see how the pool fits around everything else in a year of preventive work, try the preventive maintenance schedule builder. For the rest of the property, the hotel preventive maintenance checklist covers every area by frequency.