My second post here, still working on my signature..
Anyhow, IG, 25K, cast concrete walls, 8" thick, ceramics tiled. For some reason I need to add another 1-1/2" or two pvc pipes thru the pool wall. I do have an access to parts of the backside of the walls. what I ask is what size of hole to drill in the wall in order to accommodate 1-1/2" PVC pipe, and how and with what to seal it good. The drilling itself will be done using a diamond core bit, starting obviously from the inside tiled surface.
Waiting eagerly for any suggestion!