I dont know how much flow I have honestly. I couldn't give an estimate either. The only flow is from the HOB filter.
its really not going to do much besides move the surface...however....
Do you have a biowheel in your filter? if so- you are potentially making a very large mistake. Its a very common mistake made by lots of new people in the hobby.
If not, then good.
Let me know what you have in your set up and ill walk you through what yoiu need to do. If you would like to come visit and see my setup- just PM me and we can set up a time.
Regards,
Paul.