Hi, Thanks that is really interesting and helpful. With regards your problem for the other side my other half who is dosing opened one eye and suggested putting a block of wood against the other side or try tapeing the glass! Im hoping he knows what he is doing as he would be the one doing the drilling - I can see it will be me holding the hose (and getting shouted at if it goes wrong). Everyone seems to be drilling the back because I want the hole for drainage (my home made waterfall keeps dumping large quantities of water into the tank and my efforts to stop it happening arnt working - yet!) I actually wanted to put one in the side do you think it would make a difference?

All the best with your ideas for a waterfall, I have been thinking of something similar for my small tank as because of its size it is really not possible to have the water sorce in the tank which is what I have done with the large tank.

I will study all the various links and get my drill person to do the same (when he is more awake lol) The big tank is stripped down at the moment and it would be a good time to put a drain in. Thanks again.