Bioreactor systems and controlled operation of bioreactor systems are disclosed herein. The bioreactor systems can include at least one bioreactor chamber, at least one reservoir, a plurality of sensors, and a fluid circuit. The operational methods disclosed herein are directed towards growing cells or tissue while measuring various parameters, and a controlled operation of the various parameters during the operation of the bioreactor systems. The controlled operation of the parameters includes, for example, cell concentration; a rate of flow; a volume; a pH; a temperature; a level of oxygen; a level of carbon dioxide; a level of bicarbonate ion; nutrient compound; and any combination thereof.