Test strips and liquid drop kits handle routine pool chemistry monitoring effectively. But there are situations where the precision of a pool store analyzer or dedicated lab test provides information that home testing simply cannot. Knowing when to upgrade from strips to professional analysis — and what those tests actually reveal — prevents chemistry mistakes that cost far more than the test itself.
| Parameter | Test Strips | Drop Kit (Taylor) | Pool Store Analyzer | Lab Test |
|---|---|---|---|---|
| Free chlorine | Fair (±1 PPM) | Good (±0.2 PPM) | Good (±0.1 PPM) | Excellent |
| pH | Fair (±0.2) | Good (±0.1) | Excellent | Excellent |
| Alkalinity | Poor (±30 PPM) | Good (±10 PPM) | Good | Excellent |
| Calcium hardness | Poor | Good (±25 PPM) | Good | Excellent |
| CYA | Very poor | Fair (±10–20 PPM) | Good | Excellent |
| Metals (iron, copper) | Not available | Add-on kit | Usually available | Excellent |
| TDS | Not available | Not available | Usually available | Excellent |
| Phosphates | Not available | Not available | Sometimes available | Excellent |
Cyanuric acid testing via home test kit (the turbidity/cloudiness method) is notoriously unreliable. The test is highly subjective — different people reading the same sample get different results, sometimes 20–30 PPM apart. When CYA is approaching the 80–100 PPM threshold where action is required, a pool store analyzer result is worth getting before committing to a partial drain. Draining 5,000 gallons unnecessarily is expensive; having an accurate CYA reading prevents that.
The most common cause of unexplained pool staining or water discoloration that isn't algae is metal contamination — iron and copper being the primary culprits. Iron creates rust-orange staining on pool surfaces and turns water brown. Copper (from copper algaecides or corroding copper pipes and heat exchangers) turns water green and creates blue-green staining on light-colored surfaces.
Standard test kits don't test for metals. If a pool has unexplained staining or discoloration with otherwise correct chemistry, a metals test is the diagnostic step. Most pool supply stores can test for iron and copper for $10–$20. National pool water testing labs (such as Taylor Technologies or Watersafe Pool Complete test kits by mail) provide comprehensive metals panels for $30–$60.
When filling a new pool or after a full drain and refill, getting a complete baseline panel from a pool store analyzer is worthwhile. This captures the starting TDS, metals content in your local water supply, and a highly accurate alkalinity and calcium hardness reading — all of which affect how much startup chemistry is needed and in what order. A miscalculated startup can take weeks to correct.
Many service professionals bring a water sample to the pool store at spring opening rather than relying on field test kits alone. This is good practice, particularly for the CYA reading after months of off-season trichlor tablet use, and for a baseline calcium hardness reading that will inform the season's balancing decisions.
A bad sample collection undermines even the best lab test:
Log pool store test results in PoolLens alongside your regular field readings. Pool store analyzers often use calibrated digital instruments that catch parameter drift your test kit might miss. Having both data streams in one log helps you correlate field readings against a reliable reference point.
| Test | Typically Free | Typically Paid |
|---|---|---|
| Free and total chlorine | Yes | — |
| pH | Yes | — |
| Alkalinity | Yes | — |
| Calcium hardness | Yes | — |
| CYA | Yes | — |
| Salt | Usually | — |
| Iron | Sometimes | Usually $5–$15 |
| Copper | Sometimes | Usually $5–$15 |
| TDS | Sometimes | Usually $5–$15 |
| Phosphates | Rarely | Usually $10–$20 |
Track chemistry readings from test strips, drop kits, and pool store analyzers in one place with PoolLens. Free for pool service professionals and homeowners — offline-first, no account required.
Open PoolLens Free →Professional pool water lab analysis tests for all standard parameters (chlorine, pH, alkalinity, calcium hardness, CYA) plus extended parameters including TDS, metals (iron, copper, manganese), phosphates, and sometimes biological indicators. Lab accuracy on CYA, TDS, and metals is significantly better than test strips or basic drop kits.
Most pool retail stores (Leslie's, Pinch A Penny, local independents) offer free computerized water testing. Bring a water sample in a clean container — ideally collected from 18 inches deep, away from inlets. Free tests typically cover chlorine, pH, alkalinity, calcium hardness, CYA, and salt. Metals, TDS, and phosphates usually cost extra or require a lab kit.
Lab testing is most accurate. Liquid drop kits (Taylor K-2006) are nearly as accurate for most parameters. Test strips are least accurate, particularly for CYA (notoriously unreliable on strips) and alkalinity. For routine weekly monitoring, test strips or a basic drop kit are adequate. For CYA confirmation, calcium hardness baseline, or metals testing, a lab or pool store analyzer is worth it.
Test for metals when: water appears green or brown without algae, staining appears on pool surfaces (blue-green = copper, rust-orange = iron), after filling from a well water source, after adding algaecides containing copper, or when pH and chlorine are balanced but water still has color. Metals tests are typically $10–$25 at pool supply stores.
TDS (total dissolved solids) is the cumulative concentration of all dissolved substances in the water — minerals, salts, chemicals, and organic matter. Normal pool TDS is 300–2,000 PPM. TDS above 3,000 PPM (non-salt pool) reduces chemical effectiveness and creates water that feels heavy or looks hazy. High TDS eventually requires a partial or full water replacement — there is no chemical that reduces TDS.