the Laguna Max-Flo 2400 I'm planning to use has an out put of 1.5 in that why i was going with that for the inlet size for the stock tank but I guess i can upgrade to a 2in pipe. my real question was if a 2 in pipe coming out of the shower drain would be big enough. or i need to find another way to build a weir. the 2in coming out of the filter will go to a Savio 16" Water Weir as that is the size pipe it uses. thanks for the help. i got some more digging done today and the first row of cender blocks for the wall set in place to check the size and look. still need to dig the foundation for the wall.