HTH Algaecide Black Micro (1L) is a high-potency, non-foaming concentrated chemical treatment specifically engineered to eradicate and prevent the growth of "Black Algae" in swimming pools. Unlike standard green algae, black algae (Phormidium) forms deep-rooted, multi-layered colonies with a protective waxy coating, requiring this specialized "micro" formula to penetrate the cell walls and ensure a total kill.
Technical Specifications
- Active Ingredient: Complex Polymeric Quaternary Ammonium Compound.
- Target: Black Algae, Blue-Green Algae, and resistant Mustard Algae.
- Volume: 1L (Concentrated liquid).
- Formulation: Non-foaming and non-metallic (will not stain pool surfaces).
- Compatibility: Safe for use in Marbelite, Fiberglass, and Vinyl-lined pools.
Key Performance Features
- Deep-Penetration Technology: The "Micro" formulation is designed with a low surface tension, allowing the chemical to soak into the porous surfaces of grout and marble plaster where black algae roots itself.
- Waxy-Coating Dissolution: Specifically targets the protective mucilaginous sheath that black algae produces to shield itself from standard chlorine levels.
- Non-Foaming Stability: Unlike lower-grade algaecides, HTH Black Micro does not create unsightly foam or "suds," even in pools with high-velocity jets, rim-flows, or Fluidra water features.
- Clarifying Secondary Effect: The polymeric nature of the algaecide acts as a mild flocculant, helping to clump dead algae particles together so they can be more easily trapped by the sand filter.
- Sustained Residual Protection: When used as a maintenance dose, it creates an invisible chemical barrier that prevents new spores from taking hold during the high-light, high-heat conditions of April 2026.
Professional Usage & Application Tips
- Mechanical Disruption: CRITICAL. Before adding the algaecide, you must vigorously brush the black algae spots with a stainless steel pool brush (for Marbelite) or a stiff nylon brush (for Fiberglass). This breaks the waxy "cap" and allows the chemical to reach the living cells.
- The "Shock" Sequence: For best results, shock the pool with HTH Granular+ Chlorine 24 hours before adding the Algaecide Black Micro. The high chlorine level weakens the algae, making the algaecide treatment significantly more effective.
- Circulation Protocol: Pour the 1L dose directly into the weir or slowly around the perimeter of the pool while the pump is running on the "Filter" or "Circulate" setting. Keep the pump running for at least 12 to 24 hours to ensure even distribution.
- Filter Maintenance: Once the algae turns grey or white (indicating it is dead), vacuum the debris directly to "Waste" to prevent clogging the sand filter. Follow up with a backwash and rinse cycle.
- Water Balance: Always ensure your pH is between 7.2 and 7.6 before treatment. Algaecides lose up to 50% of their efficacy if the water is too alkaline.
Common Use Cases
- Remedial Treatment: Eradicating established black algae "spots" in the corners and steps of older Marbelite pools.
- Post-Rain Recovery: Preventing algae blooms after heavy Heidelberg afternoon thunderstorms which wash organic matter and nitrates into the water.
- Winterizing: Adding a final dose before the colder Winter 2026 months to keep the water clear while the pump run-time is reduced.
- High-Load Maintenance: Extra protection for commercial or high-traffic home pools where bather load fluctuates.
Pro Tip: If you have a stubborn spot on a step, turn off the pump and use a small section of PVC pipe to "target pour" a small amount of the concentrated liquid directly onto the spot. Let it sit for 10 minutes before restarting the pump. Always wear your Wayne Gumboots and Dromex gloves when handling pool chemicals to protect against accidental splashes. Store the 1L bottle upright in a cool, dry spot away from your Cadac Gas Cylinders and flammable liquids.



