Newa Micro-Jet Pumps are very reliable, fixed-flow pumps, suitable for many hydroponic systems.
For use with 12mm irrigation pipe and with a pumping height of 45cm, they're small and easy-to-clean, and each one has an air intake 'venturi' to add oxygen directly into the nutrient supply.
Available in two different flow-rates: MC320 Oxy - 320l/h, MC450 Oxy - 450l/h.