Pool Algae Treatment: The Complete Guide to Killing and Preventing Algae
Recommended Products
As an Amazon Associate, we earn from qualifying purchases. These are products we genuinely recommend for treating pool algae.
In The Swim Cal-Hypo Shock 24-Pack (~$62), Calcium hypochlorite shock is the best weapon against algae. This 24-pack gives you enough to treat even severe blooms. No CYA added.
Taylor K-2006 Complete Test Kit (~$90), You can’t treat what you can’t measure. The gold standard for pool water testing, measures FC, CC, pH, alkalinity, calcium hardness, and CYA.
Pool Mate Algaecide 60 (~$15), Non-foaming algaecide for maintenance dosing. Great for weekly prevention once you’ve killed the existing algae.
Lalapool 18″ Pool Brush (~$14), Heavy-duty nylon bristle brush for scrubbing algae off walls and floors. Wide 18″ head covers more surface area per pass.
In The Swim Liquid Chlorine 4-Gallon (~$42), Liquid chlorine (sodium hypochlorite) is fast-acting and adds zero CYA to your pool. Ideal for shocking algae blooms.
Pool Mate CYA Stabilizer 7lb (~$30), If your CYA is low (below 30 ppm), you need stabilizer to protect your chlorine from UV breakdown. Critical for outdoor pools.
Calculate It Instantly with Pool Chemical Calculator
Stop guessing how much shock your pool needs! The Pool Chemical Calculator app tells you exactly how much of each chemical to add based on your pool’s size and current readings.
Chlorine, pH, Alkalinity, Calcium Hardness & more
Works for all pool types, chlorine, salt water, above ground
Free to download
Frequently Asked Questions
How long does it take to treat pool algae?
Green algae can typically be cleared in 24–48 hours with proper shocking and filtration. Yellow algae may take 3–5 days, and black algae can take 1–2 weeks of aggressive treatment including repeated brushing and shocking.
Can you swim in a pool with algae?
No, you should not swim in a pool with visible algae. Algae itself isn’t necessarily harmful, but it creates an environment where dangerous bacteria like E. coli can thrive. Additionally, algae makes surfaces slippery and increases the risk of falls.
How much shock do I need to kill algae?
The amount depends on your pool size, current chlorine level, and CYA level. As a general rule, you need to reach shock-level chlorine: CYA × 0.4 for green algae, CYA × 0.5 for yellow, and CYA × 0.6 for black. Use the Pool Chemical Calculator for precise dosing.
Why does my pool keep getting algae?
Recurring algae usually indicates one or more ongoing issues: insufficient chlorine levels, poor circulation (dead spots in the pool), high CYA levels reducing chlorine effectiveness, inadequate filtration time, or inconsistent water testing and maintenance.
Is algaecide enough to kill pool algae?
No. Algaecide alone is not strong enough to eliminate an active algae bloom. Chlorine (shocking) is the primary treatment. Algaecide works best as a preventive measure, used weekly to prevent algae from establishing in the first place.
