For many years reef hobbyists have had success lowering excessively high phosphate levels with products such as SeaChem's PhosGuard. Some hobbyists, however, have avoided using this type of phosphate remover because they use aluminum oxides to bind the phosphate. Aluminum oxide does remove phosphate, but isn't an ideal product for a reef tank. First, while aluminum oxide can reduce seriously high phosphate levels, it often leaves enough phosphate in the water for nuisance algae to remain a problem. A second issue is the presence of aluminum in the filter material. The material has to be washed thoroughly to remove fine aluminum particles, but even if washed the material can increase aluminum levels in a tank.