(05/16/2008) - Be careful that your overflow tubes do not hang off and create pressure on the unit. The plastic white rods are very flimsy and bend easily. I have this unit on 1/2" thick glass and even with the 2 thumb screws tightened and with the unit well aligned, i can see the plastic bending. The 1" PVC connectors seen on the pic above are NOT glued to the black acrylic and you have to be careful that they dont dislodge or you can have a very bad accident. I'm looking into glueing them permatently.