I am about to install a new above ground pool but it will be semi inground. The pool is a Radiant Metric 27' round. These are built from aluminum with a foam insulation in between the walls. What kind of magnesium anode and where can i purchase to add to the install? Also when i bond pool does it have to be 18" away from pool and only 4 to 6" deep or can it be lower in ground and closer since i dug an extra foot around it and pool will be roughly 26" down in ground.