A fluid circulation system (1300; 1400; 1500) comprising: a fluid mixing chamber; first (1302; 1402) and second (1312; 1412) open fluid chambers in fluid communication with the fluid mixing chamber, each open fluid chamber having a microfluidic fluid leveling conduit (1420; 1434; 1442) having an orifice (1422; 1436; 1444) disposed in the open fluid chamber at a minimum fluid level (1306; 1406) associated with a corresponding minimum fluid volume; a first pump (1320; 1426; 1440; 1458; 1510) in fluid communication with the microfluidic fluid levelling conduits of the first and second open fluid chambers; a second pump in fluid communication with at least one of the first and second open fluid chambers and the fluid mixing chamber; and a controller coupled to the first and second pumps, and configured to: cause the first pump to generate a first direction of fluid flow during a first time period between the first and second open fluid chambers through the microfluidic levelling conduit of the first open fluid chamber such that a fluid level in the first open fluid chamber drops to about its corresponding minimum fluid level; cause the first pump to generate a second direction of fluid flow during a second time period between the first and second open fluid chambers through the microfluidic levelling conduit of the second open fluid chamber such that a fluid level in a second of the two open fluid chambers drops to about its corresponding minimum fluid level (1316; 1416); and cause the second pump to generate a flow of fluid during a third time period from one of the first and second open fluid chambers into the fluid mixing chamber. a fluid mixing chamber; first (1302; 1402) and second (1312; 1412) open fluid chambers in fluid communication with the fluid mixing chamber, each open fluid chamber having a microfluidic fluid leveling conduit (1420; 1434; 1442) having an orifice (1422; 1436; 1444) disposed in the open fluid chamber at a minimum fluid level (1306; 1406) associated with a corresponding minimum fluid volume; a first pump (1320; 1426; 1440; 1458; 1510) in fluid communication with the microfluidic fluid levelling conduits of the first and second open fluid chambers; a second pump in fluid communication with at least one of the first and second open fluid chambers and the fluid mixing chamber; and a controller coupled to the first and second pumps, and configured to: cause the first pump to generate a first direction of fluid flow during a first time period between the first and second open fluid chambers through the microfluidic levelling conduit of the first open fluid chamber such that a fluid level in the first open fluid chamber drops to about its corresponding minimum fluid level; cause the first pump to generate a second direction of fluid flow during a second time period between the first and second open fluid chambers through the microfluidic levelling conduit of the second open fluid chamber such that a fluid level in a second of the two open fluid chambers drops to about its corresponding minimum fluid level (1316; 1416); and cause the second pump to generate a flow of fluid during a third time period from one of the first and second open fluid chambers into the fluid mixing chamber. cause the first pump to generate a first direction of fluid flow during a first time period between the first and second open fluid chambers through the microfluidic levelling conduit of the first open fluid chamber such that a fluid level in the first open fluid chamber drops to about its corresponding minimum fluid level; cause the first pump to generate a second direction of fluid flow during a second time period between the first and second open fluid chambers through the microfluidic levelling conduit of the second open fluid chamber such that a fluid level in a second of the two open fluid chambers drops to about its corresponding minimum fluid level (1316; 1416); and cause the second pump to generate a flow of fluid during a third time period from one of the first and second open fluid chambers into the fluid mixing chamber.