In addition to using the pvc as a structure to mount rock to, you could consider using it and the holes you drill through it as a spray bar on a closed loop system to push additional flow through your rock. That would, however, involve drilling the bottom of your tank and installing bulk heads. Just a thought. Otherwise it is looking snazzy, and I can't wait to see the finished product. In addition to using the pvc as a structure to mount rock to, you could consider using it and the holes you drill through it as a spray bar on a closed loop system to push additional flow through your rock. That would, however, involve drilling the bottom of your tank and installing bulk heads. Just a thought. Otherwise it is looking snazzy, and I can't wait to see the finished product.