Algal blooms happen when waste water from farms, factories and dwellings carries large amounts of normally scarce nutrients like nitrogen, potassium and phosphorous into rivers, lakes and seas. Algae, often unicellular ones, lap these nutrients up and breed like billy-o. These blooms are occasionally dangerous, if the algae involved are toxic, and are generally regarded as undesirable. But what if it were possible to control an algal bloom, and use it to absorb such nutrients before they escape to the wider environment? That is the idea behind a technology developed by Algal Scientific, of Northville, Michigan. Algal's researchers are not the first to try to control pollution with algae. But they think they are the first to have succeeded in a commercially viable way, for they have installed a plant at the Budweiser brewery in Idaho Falls.