For connecting a 50 and 20 gal tank, it hardly seems worth it for the best way in running any two tanks off the same filtration system is by a sump. Myself, I been very successful with my 70 and 130 gal that runs off from a 40 sump with an ER skimmer. Also not bother in asking of the setup on my pair of tanks because it isn't a cheap setup for I have everything on these tanks from that in which I already had mentioned and chillier with UV. This setup was my own idea, only I not needed the UV, Jeff added that for within an eel only tanks a UV is in my thoughts wasteful on having.