ELx405 self-maintaining microplate washer uses Ultrasonic Advantage built-in ultrasonic cleaning to aid in routine maintenance, specifically to help prevent clogging in the manifold due to protein or salt crystal build-up. The instrument features include Dual-Action manifold for precise overfill washing and overflow protection, sensitive cell washing capabilities for loosely adherent cell layers. Internal positive displacement pump eliminates the use of pressure delivery systems and allows the use of any size dispense reservoir. Built-in priming trough allows automatic manifold priming and rinsing during both operation and maintenance modes and eliminates the need for 'blank' plates when used in automated robotic systems. Fully variable dispense volumes, flow, and aspiration rates provide 'total control' of the washing cycles from a gentle cell-washing application to vigorous wash for high-binding assays.