What to Test (and When)
Water care is science. Ally keeps it simple and exact. Use this guide to know what to test, when to test it, and what matters for your pool, spa, aquarium, or pond.
Universal Rules (for all water types)
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Sample smart: Rinse the container with pool/tank water, collect mid‑depth away from returns/surfaces, and test within 5 minutes.
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Test consistently: Same time of day, same test method brand where possible.
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Change → mix → wait → retest: After dosing, circulate and wait the appropriate time before re‑testing (see each section).
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Log everything in Ally: We track trends and flag drifts early.
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One change at a time: Dose, wait, retest. Avoid stacking corrections.
Pools (Chlorine & Saltwater Generators)
Routine & Events
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Weekly: FC, CC, pH
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Every 2–4 weeks: TA, CH, CYA, Salt
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After heavy rain/top‑off: Test FC & pH same day; re‑check next morning.
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After a big swim day: FC & pH that night; CC next morning.
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Cloudy/green: Full panel; brush + oxidize per Ally action card.
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Opening/refill/closing: Full baseline panel.
Retest Timing
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Liquid chlorine: 15–30 min (pump on)
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Muriatic acid / soda ash: 30–60 min before pH re‑check
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Bicarbonate (TA up) / calcium chloride (CH up): 2–4 hrs
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CYA in sock/skimmer: 24–48 hrs to register
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Salt addition: 12–24 hrs for uniform mix before SWG calibration
Phenol‑red pH tests are unreliable when FC > ~10 ppm. Let FC fall before trusting pH.
For plaster pools, aim LSI ≈ −0.1 to +0.3 to minimize scale/etching. Ally calculates this for you.
Spas & Hot Tubs
Routine & Events
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Before each soak: Sanitizer & pH
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Weekly: TA & CH; shock if CC > 0.5 ppm or after heavy use
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Drain & refill: Typically every 4–8 weeks; reset baseline panel
Retest Timing
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Adjustments: 20–30 min circulation
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After shock: Follow label wait‑time; retest sanitizer before soaking
Freshwater Aquariums
Routine & Events
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New tank / cycling: Ammonia & nitrite daily, nitrate every 2–3 days
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Established tank: Weekly nitrate & pH; monthly KH/GH
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Event tests: After large water changes, adding fish, illness/loss, or algae blooms
Retest Timing
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After conditioners that detox ammonia: some kits (Nessler) show false positives for 24–48 hrs. Prefer salicylate‑based ammonia tests or wait a day.
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After buffers/ferts: 1–2 hrs for KH/pH to settle; 24 hrs to evaluate nitrate/phosphate changes.
Planted tanks (CO₂): Track KH & pH to infer CO₂; keep nitrate 5–20 ppm and avoid zero phosphate.
African cichlids: Higher pH 7.8–8.6 and KH/GH 8–20 dKH/dGH.
Reef / Saltwater Aquariums
Routine & Events
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2–3×/week: Alkalinity
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Weekly: Nitrate, phosphate, calcium, magnesium (and verify salinity whenever you mix water)
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Event tests: New livestock, media changes, dosing tweaks, or visible coral stress → check alk + salinity same day; nutrients within 24–48 hrs
Retest Timing
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After dosing (2‑part/alk): Re‑check alkalinity after 2–4 hrs; nutrients in 24 hrs
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Refractometers: Calibrate with 35 ppt solution (not RO/DI) for correct scale
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Skimmer changes: Wet skimming can shift salinity—test after large skimmate pulls
Advanced: Only test iodine/strontium/trace if you intentionally dose them. Quarterly ICP is a good snapshot for trace/metals.
Outdoor Ponds (Koi/Goldfish)
Seasonal Notes
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Spring warm‑up: Biofilters lag, test ammonia/nitrite more often.
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Summer heat: Aerate; oxygen drops as temperature rises.
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Fall leaf drop: Organics elevate ammonia; skim and test.
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Winter: Light feeding; monitor ammonia during warm spells.
Sampling, Gear & Accuracy
Best Sampling
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Pools: Elbow‑deep (12–18"), away from returns/skimmers, not right after dosing.
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Aquariums/Ponds: Mid‑water; avoid right after feeding/dosing. If microbubbles at the return, sample away from it.
Test Methods
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Strips: Fast; good for trends; ±0.5–1.0 unit precision.
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Liquid/titration kits: Most reliable for FC/CC, alkalinity, calcium (pool) and ammonia/nitrite/nitrate (aquarium).
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Digital meters: Great for pH, salinity, TDS, ORP—require calibration & clean probes.
Calibration & Care
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pH meters: 2‑point calibration monthly or when readings drift.
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Reagents: Replace annually; store cool & dark.
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Refractometer: Calibrate at 35 ppt; clean lens with RO/DI.
Common Pitfalls
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High chlorine (> ~10 ppm) skews phenol‑red pH readings.
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Ammonia conditioners can confuse Nessler ammonia kits for 24–48 hrs.
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Cloudy samples can skew color reads—filter a small sample and retest.
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Swing‑arm hydrometers often read low; verify with a refractometer.
“Is This Urgent?”
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Ammonia or Nitrite > 0 ppm (any aquarium/pond): Urgent. Increase aeration, partial water change, use conditioner if available, retest in 2–4 hrs.
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Pool FC < 1 ppm with bathers: Urgent. Dose to target before use and re‑check in 30 min.
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Reef alkalinity swing > 0.5 dKH/day: High priority. Stabilize dosing; verify salinity.
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pH outside 7.2–7.8 (pools/spas) or < 6.4 / > 8.6 (freshwater): High priority. Adjust slowly; protect biofilter.