This bulb has been designed specifically by arcadia to compatibly fit the laguna pressure flo 12000 uvsr green water caused by millions of suspended microscopic algae is the curse of many pond keepers so what is the best way to control this nuisance a good quality pump filter and ultra violetclarifier system of a capacity to suit the size of the pond is all that is requiredr as water is pumped through the clarifier the single celled algae are exposed to high levels of uvc radiation emit