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What if… adjust and watch the balance
More
What if… adjust and watch the balance
Water balance (LSI) − etching · 0 balanced · + scaling
Bromine ppm · band = target
pH
Total alkalinity ppm
Calcium hardness ppm
Temperature °F
Bromine feeder
Patterns
LSI calculator
Langelier Saturation Index, computed with the Wojtowicz (2001) revised equation and temperature-dependent constants — the same basis as the Orenda calculator, not the 1964 chart. Negative water dissolves plaster, grout and heater copper; positive water deposits scale. Aim 0 to +0.3.
How LSI is computed (and why it differs from charts)
Close the facility now if
Any of these is a closure condition under WAC 246-260-131(11) and King County's closure guidance. Close, fix, retest, log the closure and the reopen time. Reinspection fee is 50% of the operating permit.
- Bromine below 2.5 ppm pool / 4.0 ppm spa, or above 10 ppm anywhere (Table 111.1)
- pH below 7.2 or above 8.0 (Table 111.2)
- Spa water above 104 °F
- Main drain or pool bottom not clearly visible (clarity)
- Drain cover broken, missing or loose (entrapment — federal VGB Act + WAC 131(2)(f))
- Recirculation pump, filter or feeder not running — treatment must be continuous 24 h during use
- Feces, vomit, blood, sewage or unknown material in the water — close until cleaned and disinfected
- Barrier gate won't self-close and self-latch — lock it until fixed
Report within 48 hours
Drowning (fatal or not), death, serious injury, or illness associated with the facility: call Public Health Seattle & King County 206-263-9566 within 48 hours and submit the Injury or Illness Report Form (copies in the compliance binder). WAC 246-260-121(1).
Required routine
| When | What | Rule |
|---|---|---|
| Every 24 h | Bromine residual · pH · spa temperature (water over 95 °F) · treatment flow rate · chemicals added · any contamination · drain covers intact · gate latches · clarity · skim floating material | WAC 121(3), 111(4), 131(2) |
| Weekly | Total alkalinity (required). Calcium hardness and TDS (not required — needed for LSI, which protects plaster and both heaters) | WAC 121(3)(a)(iii) |
| Per formula | Drain, clean and refill the spa every ? days = 630 gal ÷ 3 ÷ ? users/day. Last drain: not logged | WAC 131(4) |
| Always | Keep an extra cartridge for the spa filter · keep signage, rules and first-aid kit current · keep these records 3 years and available to the inspector | WAC 131(2)(g), 121(3)–(4) |
Targets vs. legal limits
| Test | Aim (best water) | Legal limit (close if outside) |
|---|---|---|
| Bromine, pool | 4–6 ppm | 2.5 – 10 |
| Bromine, spa | 4–8 ppm | 4.0 – 10 |
| pH | 7.4–7.6 | 7.2 – 8.0 |
| Total alkalinity | Pool 70–100 (aim 80) · Spa 50–80 (aim 60). Low on purpose: alkalinity is only a pH buffer, and the more you carry the faster CO₂ loss pushes pH up and the more acid you burn. The company sheet's 80–120 is a generic pool figure, not a rule. | no legal range — test weekly (WAC 121) |
| Calcium hardness | 250–400, aim 300 both vessels. Calcium carries the LSI so alkalinity can stay low; it does not move pH. (ANSI/APSP/ICC-11: 150 min, 1,000 max) | no legal range — LSI decides |
| LSI | 0 to +0.3 | no legal range — protects plaster & heaters |
| Spa temperature | 100–104 °F | max 104 |
| TDS | under fill water + 1,500 | no legal range — drain when high |
Sources: WAC 246-260-111, -121, -131 and Appendix A (246-260-999), read Sept 2026. The Avenue5 log sheet's pH 7.2–7.6 is a company target, tighter than the law.
What is verified, what is estimated
| Item | Basis | Status |
|---|---|---|
| Legal limits, routine, closure rules | WAC 246-260-111/121/131 and Appendix A, read Sept 2026 | Verified |
| Volumes | Stamped FINAL Pool Data Forms: 15,240 and 630 gal | Verified |
| Drop conversions | Taylor K-2006 reagent values | Verified |
| LSI | Wojtowicz 2001 revised equation, Plummer & Busenberg constants, Davies activity, ion pairing. Matches the paper's table ±0.02. Two Orenda readings (spa +0.03, pool −0.12, both with TDS blank) are reproduced exactly at an assumed TDS of ~1,300; the 0.03–0.05 gap at our 1,000 default is the blank-TDS assumption, not the equation | Verified |
| Bicarb, calcium doses | Molecular weight and purity | Chemistry |
| pH Minus / pH Up doses | Carbonate-equilibrium model from your TA and pH. Closed-system minimum; CO₂ loss can raise real demand 20–40%, so stage and retest | Model — retest |
| Bromine tablets | ~8 ppm per lb per 10,000 gal (66% available bromine); release rate depends on the feeder | Estimate |
| Shock, Thio-Trine | Product label rates; chlorine × 2.25 on the bromine scale | Label |
| TDS | Assumed 1,000 ppm until you enter a reading | Assumed |
Every calculation has a "?" or "Show the math" next to it. If a number looks off, the math is the first place to look.
Fresh-fill startup (bromine)
Seattle tap water is very soft: alkalinity ~20–30, calcium ~15–25, pH ~7.5–8. Left alone it is aggressive (LSI around −1.5) and will etch plaster and the heaters. Do these in order and log every addition:
- Circulate, test the fill water (Br, pH, TA, CH, temp). Heaters off until step 3 is done.
- Alkalinity first → 80 pool / 60 spa with sodium bicarb. Broadcast with pump running; retest after 4–6 h. (Dose tab does the math.)
- Calcium next → 300 in both with calcium increaser, pre-dissolved, added slowly. Retest next day.
- pH → 7.4–7.6. Bicarb pushes pH up; use pH Minus in half doses.
- Sanitizer: load the feeder with tabs, dial high until bromine reaches 4–6 ppm, then back the dial down. A bromine reserve (bromide) builds as tabs dissolve; the first days burn faster than steady state.
- LSI check — once 0 to +0.3, heaters on. Spa to 102–104 °F; re-check LSI hot (temperature raises it).
- Reopen only when bromine, pH, temp and clarity are all inside the legal limits, and log the reopen.
Dosing reference — bromine pool & spa
Every amount the app suggests comes from these rates, scaled to the vessel (pool 15,240 gal · spa 630 gal). Per 10,000 gallons:
| To | Use | Amount per 10,000 gal | Notes |
|---|---|---|---|
| Raise alkalinity 10 ppm | Sodium bicarbonate | 1.4 lb (≈ 3 cups) | Broadcast. Raises pH a little. Retest in 6 h. |
| Raise calcium 10 ppm | Calcium chloride (77%) | 1.2 lb (≈ 2 cups) | Bucket of water first — it heats. 24 h to settle. |
| Lower pH 0.2 | pH Minus (sodium bisulfate) | ~1 lb at TA 80 (more at higher TA) | The app sizes this from your alkalinity. Half now, half after a 1 h retest. Consumes alkalinity. |
| Raise pH 0.2 | pH Up (soda ash) | ~6 oz | Raises alkalinity too. Fix low TA with bicarb first. |
| Raise bromine 1 ppm | Bromine tablets in the feeder | ≈ 1 tab per 8 ppm | Slow — days, not hours. This is the normal daily sanitizer. The feeder dial sets the rate. |
| Raise bromine 1 ppm now (shock) | Liquid chlorine 10% | 4.8 fl oz per ppm on the bromine scale | Chlorine in a bromine pool does not make a "chlorine pool": it oxidizes the bromide reserve back into active bromine, so it reads on the bromine scale ×2.25. 10.7 fl oz raises 2.25 ppm bromine. Pushes pH up — retest. |
| Shock (alternative) | Cal-hypo (Re-Fresh 59.5%) | 2.2 oz per 2.25 ppm bromine | Adds calcium each time. Never near the tablets. Prefer liquid chlorine here. |
| Lower bromine 1 ppm | Thio-Trine | 1 oz | Half at a time; easy to overshoot to zero. |
Order of operations: alkalinity → calcium → pH → sanitizer → check LSI. One product at a time; retest between. Settling times the app enforces: pH Minus / pH Up 1 h · liquid chlorine 2 h · bicarb 6 h · calcium 24 h · tablets and feeder-dial changes 2 days.
Dilution: a pool backwash replaces about 345 gallons per inch the level drops (554 sq ft). Seattle fill water is ~25 ppm alkalinity, ~20 ppm calcium, 0 bromine — so every inch of backwash lowers alkalinity and calcium by about 2% and the next test will read a little lower. A spa drain resets everything to fill water: follow the fresh-fill steps below.
How bromine works here
The feeder dissolves BCDMH tablets, releasing hypobromous acid (the sanitizer). When it kills something it becomes bromide, which sits in the water as a reserve; any oxidizer — the tablets' own chlorine half, or a chlorine shock — turns bromide back into active bromine. That is why chlorine shock in a bromine pool reads on the bromine scale (×2.25) and why the reserve makes dosing steadier over time. Tablets are acidic: expect pH and alkalinity to drift down; bicarb is your main correction. Bromine has no stabilizer, so the indoor location is what protects it — cyanuric acid does nothing for bromine and is not used here.
Test kit (Taylor K-2006 FAS-DPD): bromine on a 10 mL sample, each R-0871 drop = 0.5 ppm chlorine × 2.25 = 1.125 ppm bromine. Alkalinity and calcium on 25 mL samples, each drop = 10 ppm. Combined chlorine has no meaning in a bromine pool — bromamines are still sanitizers — so it is not tracked. Very high bromine (over ~10) bleaches the pH and TA indicators: retest those once bromine is back in range.
Contamination response
Formed stool: close, remove, net/vacuum to waste, raise bromine and hold ≥ 30 min at ≥ 4.5 ppm (2 ppm chlorine-equivalent) with pH ≤ 7.5, filter running; reopen after retest.
Diarrhea or vomit with feces: Cryptosporidium risk — close, remove, then hyperchlorinate (CDC: 20 ppm free chlorine for 12.75 h at pH ≤ 7.5; on the bromine scale that reads ~45 ppm) — call King County first (206-263-9566) because the bromine reserve complicates the math. Filter for the full period, then backwash to waste, neutralize with Thio-Trine, retest everything.
Blood: no closure required if disinfectant is in range; clean deck surfaces. Log every incident (WAC 121(3)(b)(iii)).
Chemical safety
Never mix products. Keep cal-hypo away from anything organic or acidic and away from the bromine tabs (fire risk). Add chemicals to water, never water to chemicals. Never put a chlorine product in the bromine feeder or a bromine tab in a chlorine feeder. Store dry and ventilated, off the floor, labels facing out. Eyewash within reach.
Settings
Account & sync
Record
Newest first. Print gives a clean monthly report for the binder (3-year record); CSV pastes into the Avenue5 log.