My pool is looking good, but I want make sure I keep the algae away. I want to add algaecide (the polyquat 60) and just am checking if this is the right product. Amazon.com : Kem-Tek KTK-50-0006 Pool and Spa 60-Percent Concentrated Algaecide, 1 Quart : Swimming Pool Algaecides : Patio, Lawn Garden Also where else is it available anywhere for cheaper?