DIY CO² External Reactor

[izzat]

Hi guys

What pointers should be taken into consideration to maximise the efficiency of a DIY CO² External Reactor?
What type of design(s) are capable to maximise the efficiency?
What design aspect(s) could also maximise the efficiency?

Also apperciate any other pointers as to maximise the efficiency of a DIY CO² External Reactor.
I am running the DIY CO² External Reactor with a 3000LPH external pump

Thanks for your imput