Yes, there are two 2" holes in the bottom of the tank as well. Originally I had intended to run a 1" inlet and 1" outlet with an adaptive stockman/durso overflow standpipe. It didn't workout though because the standpipe could not compete with the influx of water from my 70rlt. That's why I chose the back overflow. I don't know what I'll do now with the holes in the bottom... maybe I'll add an oscillating output like the oceanmotions or something.