Applied Biochemists Black Algaetrine, 1 Quart, 406303A

Black Algaetrine from Applied Biochemists is a 1 quart copper algaecide made for one job: black algae. It carries 3.07 percent active copper along with penetrating agents that push the copper into the algae cells rather than sitting on top of them.

Why black algae is different

Black algae roots into plaster and grout and grows a protective outer layer over itself. That layer is why a general purpose algaecide and a normal chlorine level often make no visible difference to it. Getting on top of it means breaking that layer open and getting a product into the colony underneath, which is what the penetrating agents in this formulation are there to do.

Dosing

For visible growth, apply 12 ounces per 10,000 gallons of pool water and vacuum out the settled debris afterwards. For heavy growth, vacuum, clean and scrub the walls first, then dose at the same rate and vacuum again. Once the pool is clear, a maintenance dose of 6 ounces per 10,000 gallons every 5 to 7 days keeps it that way, and that interval should tighten when the weather is hot or the pool is heavily used.

In use

Swimming can carry on without a wait, and used at the stated doses the product will not discolor the water. It is listed for above ground and in ground pools, residential and commercial water, spas and fountains.