Back/Scale Prevention Routine

Scale Prevention Routine

Stay ahead of scale by managing CSI, brushing, and periodic descaling tasks.

When to use: High CH fill water or salt pools running in warm climates.
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Scale Prevention Playbook

Routine maintenance to prevent calcium scale in hard-water environments

CSI

Target CSI: -0.3 to +0.3

Calculate weekly using pH, TA, CH, and temperature. Adjust pH/TA to compensate for high CH.

High-Risk Scenarios
  • • Salt pools with CH above 400 ppm (SWG accelerates scale)
  • • Fill water with CH above 300 ppm (scale will worsen over time)
  • • Heated pools/spas (heat increases scale precipitation)
  • • Pools with water features (aeration drives pH/temperature up)
  • • Plaster surfaces (scale bonds more aggressively)
Scale Prevention Myths
  • MYTH: "Sequestrants remove existing scale"
    REALITY: Sequestrants only prevent NEW scale by binding calcium in solution. They don't dissolve existing deposits. Remove scale mechanically (brushing, acid wash) or chemically (careful acid treatment).
  • MYTH: "High CH is only a cosmetic issue"
    REALITY: Scale clogs heaters, damages SWG cells, reduces flow in pipes, and creates rough surfaces that harbor algae. It's a functional problem, not just appearance.
  • MYTH: "Lowering pH below 7.2 prevents scale better"
    REALITY: Low pH causes corrosion of equipment, etching of plaster, and metal staining. Target pH 7.2-7.6 based on CSI. Never go below 7.0 to chase scale prevention.
  • MYTH: "Acid washing removes scale permanently"
    REALITY: Acid wash removes scale temporarily but damages plaster surface. If root cause (high CH/CSI) isn't fixed, scale returns rapidly. Address chemistry first.
1

Weekly CSI Monitoring

Track Calcium Saturation Index to stay ahead of scale formation.

Test pH, TA, CH, and temperature weekly minimum
Calculate CSI using all four parameters (use CSI calculator)
Target CSI: -0.3 to +0.3 (balanced, no scale/corrosion tendency)
CSI above +0.3? Water is scale-forming - action required
CSI below -0.3? Water is corrosive - raise TA or pH slightly
Log CSI trends monthly to anticipate seasonal changes
2

pH & TA Management

Keep pH in lower-normal range to offset high calcium hardness.

If CH is 300-400 ppm: Target pH 7.4-7.6 (normal range)
If CH is 400-500 ppm: Target pH 7.2-7.5 (lower end)
If CH is 500+ ppm: Target pH 7.2-7.4 and plan partial drain
Maintain TA 60-80 ppm (lower = easier pH control)
Use muriatic acid for pH reduction (lowers TA simultaneously)
Avoid pH drift above 7.8 - scale risk increases exponentially
3

Surface Maintenance

Regular brushing and cleaning prevent scale deposits from hardening.

Brush tile line twice weekly minimum (scale starts here first)
Brush spillways, steps, and low-flow areas weekly
Clean waterline with tile cleaner monthly (removes oils + early scale)
Use pumice stone on tile for light scale (test inconspicuous area first)
Inspect pool lights and ladder mounts - scale builds in crevices
Brush pool floor/walls weekly if CSI consistently above +0.2
4

SWG Cell Cleaning (If Applicable)

Salt chlorine generators accelerate scale on cell plates - clean proactively.

Inspect cell every 4-6 weeks for white scale buildup
Clean when scale is visible or voltage/amperage spikes abnormally
Remove cell and soak in 4:1 water:muriatic acid solution (20 min)
Rinse thoroughly before reinstalling
If cleaning frequency exceeds monthly: lower CH via partial drain
Log cleaning dates to track scale accumulation rate
5

Sequestrant Use (If Needed)

Use chelating agents only when CSI control isn't sufficient.

Sequestrants bind calcium/metals temporarily - not a long-term fix
Only use if CSI stays above +0.3 despite pH management
Add per label directions (typically 1 qt per 10k gal monthly)
Choose sequestrants without phosphates (feeds algae)
Sequestrants don't remove scale - they prevent new deposits
Plan partial drain if sequestrant becomes monthly requirement
6

Partial Drain Strategy

Dilute calcium hardness when it exceeds manageable levels.

Drain 1/3 to 1/2 of pool water when CH exceeds 500 ppm
Time drain during low-use season (fall/spring ideal)
Test fill water CH first - high-CH fill water limits effectiveness
Refill slowly to avoid plaster damage (especially for older pools)
Rebalance chemistry after refill (CYA will be diluted too)
Log CH reduction to estimate future drain intervals

Common Questions

What CH level requires a partial drain?

Above 500 ppm for most pools. Above 400 ppm for salt pools with visible scale issues. Test fill water first - if it's already 300+ ppm, draining provides temporary relief only. Consider RO water service or soft water fill.

Can I use calcium reducers instead of draining?

Chemical calcium reducers precipitate calcium for vacuum removal. They work but require careful execution (can cloud water, clog filters). Partial drain is simpler and more predictable for most homeowners.

How do I remove existing scale from tile?

Light scale: pumice stone + elbow grease. Medium scale: tile cleaner with diluted acid (test first). Heavy scale: professional bead blasting or careful acid wash. Always address root cause (CH, CSI) after removal.

My fill water has 400+ ppm CH - what can I do?

1) Fill with soft water or RO service, 2) Use sequestrants proactively, 3) Keep pH at lower end (7.2-7.4), 4) Plan annual partial drains, 5) Consider reverse osmosis mobile service for in-place water treatment. High-CH fill water requires aggressive prevention.

Should I turn off my SWG during high-CH periods?

Not necessary if CSI is controlled. Reduce SWG output to minimum needed for sanitation and supplement with liquid chlorine if concerned. Clean cell more frequently. Focus on lowering CH via partial drain if scale becomes problematic.

Checklist

  1. 1Track CSI weekly; drift positive? Lower pH target by 0.2 temporarily.
  2. 2Brush tile line and spillways twice weekly.
  3. 3Clean SWG cell every 6 weeks or when voltage spikes.
  4. 4Use sequestrant only if CSI control can't stay below +0.3.
  5. 5Log CH trends to anticipate partial drains if needed.

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