I have fallen in love with something called Uniseals: they're a lot cheaper
than bulkhead fittings, forgiving, and re-useable! You cut a hole a little
larger than your PVC pipe (instructions included), place the fitting into
the hole, then shove the PVC pipe through. It compresses the seal to the
sides of the hole to make it water tight. And you can slide the PVC pipe in
and out until you get the right length (for us who are measurement
challenged, or to handle the problems of settling tanks). Further, if you
decide to trash the system you're using, the Uniseal pops out for re-use!
I've used several sizes, including the 4", but they also have a 6". Aquatic
Ecosystems has them, or perhaps a search will turn them up for you.

Lee

"DesertPond" wrote in message
...
I've got a 400-gallon round galvanized tank (with liner) that I use
for quarantine purposes. I'd like to use some sort of bottom drain
setup for it but I'm not sure how to go about it. Not sure if it's a
good idea to drill a hole through the side for pipe access.

Any suggestions?

thx