Yeah, currently they are, but I am going to be soon running 2 - 4 Koralia 4's in there. I have picked up 4, but am going to start with two, one in each upper back corner almost at a 45 degree pointed to the middle, then may add two more for added circulation. With the new rock I added, I had open holes in the back, that I tucked the maxi-jets into to keep flow moving behind the rocks too.