White PVC Spring Check Valves, Slip Ends (SLIP) Low Head These pumps come with an BYC238 These pumps come with an optional fountain that has a flow control It also comes with a couple of adapters to connect the pump directly to tubing Nexus Model: Water Volume Inside Filter Amount of K1 Micro Media included Amount of K+ Media included Maximum K1 Capacity Nexus220 135 US Gallons 18 liters 50 liters 150 liters Nexus320 222 US Gallons 20 liters 100 liters 300 liters EasyPod (for comparison) 21 US Gallons 18 liters N A 18 liters Check valves are essential when using a waterfall filter in conjunction with a pond skimmer Check valves are also essential when an external pump is being used