Pool Algae Treatment

Purpose

Define the remediation protocol for a pool with visible algae growth - green water, mustard staining on walls, or black-algae spots. The treatment combines mechanical (brushing, vacuuming, filter cleaning), chemical (super-chlorination, algaecide), and time (24 - 72 hour cycles). Misdiagnosing algae type leads to incorrect treatment + the algae returns within a week.

Scope

Applies to:

• Residential in-ground + above-ground pools with visible algae
• Salt + chlorine + bromine + UV-supplemented sanitization systems

Excludes commercial pools (different cadence + chemical pathways), and pools whose chemistry is so far off that algae is the second-tier issue (those need a chemistry rebuild first).

Responsibilities

• Lead technician identifies the algae type + selects the treatment cycle
• Crew member brushes + vacuums between treatments
• Customer is briefed on the 3 - 5 visit timeline + interim swimming restriction

Procedure

Step 0 - Diagnose the type:

Step 1 - Pre-treatment baseline:

1. Test + correct chemistry: pH 7.4 - 7.6 (critical - high pH reduces chlorine effectiveness). Alkalinity 80 - 120. CYA 30 - 50 (above 80 = chlorine lock; partial drain required first).
2. Brush walls + floor aggressively. Algae releases easier under brushing.
3. Clean / backwash filter - algae will clog whatever it lands in.

Step 2 - Super-chlorination:

1. Green algae: shock to 10 - 12 ppm free chlorine. Cal-hypo or dichlor.
2. Mustard algae: shock to 20 - 30 ppm AND add mustard-algae-specific algaecide. The high shock + specific algaecide together break the chlorine-resistance.
3. Black algae: shock to 30 + ppm AND scrub each black spot with a wire brush before treatment AND apply black-algae-specific algaecide directly to the spots. Plaster pool only - wire brush damages vinyl. Black algae on vinyl liner = a pool you can't fully clear without liner work.

Step 3 - Circulate + treat (24 - 72 hours):

1. Run pump 24/7 during treatment.
2. Brush walls + floor 2 - 3 times per day.
3. Test chlorine every 6 - 12 hours; maintain shock level until clear.
4. Vacuum dead algae to waste (NOT through the filter - overwhelms it).

Step 4 - Recovery:

1. Once water is clear, allow chlorine to drift back down to 1 - 3 ppm (sun + time).
2. Backwash filter heavily.
3. Test all chemistry; rebalance as needed.
4. Re-establish recurring service schedule.

Acceptance Criteria

• Water visibility > 8 ft (residential standard)
• No algae visible on walls + floor + steps after brushing
• Chlorine + pH back to target ranges
• Filter cleaned + functioning
• Customer signs field report acknowledging the 3 - 5 visit cycle is complete

Troubleshooting

• Green algae returns within a week: chlorine isn't sustaining. Check CYA (likely > 80 ppm - chlorine lock). Partial drain + dilute. Customer may need a sustained-release chlorine stabilization upgrade.
• Mustard algae returns: spores survive on cleaning equipment. Disinfect all brushes, poles, vacuum heads, AND the pool toys before declaring it cleared.
• Black algae stays: plaster will need acid wash OR a complete pool drain to address. Black algae's root structure penetrates the plaster surface. Manage expectations: the visible spot can be partially treated but full elimination may need invasive work.

References

• NSPF / PHTA Certified Pool Operator Manual
• Algaecide manufacturer literature
• Manuall internal: Weekly Recurring Pool Service, Cloudy Pool Water - Diagnostic Tree, Pool Chemistry Quick Reference