Compared to a classic survival assay (or decay assay, inactivation assay, ...), this protocol uses predetermined virion concentrations and miniaturization to increase efficiency. Briefly, suspensions containing 50000, 5000, 500, or 50 virions/ml are prepared for each virus, these suspensions are split into aliquots, and independent aliquots are used to do an MPN-like assay after 0, 7, 14, ... days. The MPN-like assay involves distributing a 50000, a 5000, a 500, and a 50 virions/ml aliquot across 16 liquid cultures of host cells (algae) and observing the number of cultures that are lysed. Non-linear statistical models are then used to estimate the initial concentration and decline of infectious virions. See the associated manuscript for a full description and schematic figures, as well as the statistical model.