Your problem is not very clear but usually a 1/4" weep hole dilled at the top of the pipe should prevent any syphoning back into the blower. Just make sure the hole does not blow into anybody's face.
Good luck
Any air blower manufacturer will be more than happy to send you all the literature you need to design air spargers. You may want to contact hoffman for starters.
If you are working with a pressurized system there is no head, you just calculate friccion losses. At which case you just need a recirculation pump (like the big skyscrapers use) then you would just need to calculated the liquid volume in the system and the velocity at which the liquid would be...
