I built a cooler mash tun out of a 56 quart rubber maid but the hole is about an 1inch above the bottom. So i tried bulding manifold out of cpvc and it leaves about 1 inch of water, then i built one out of copper and it leaves about 3/4 of an inch. I can only get all the water out by tilting the cooler towards the ball valve.
Now my question is am I supposed to have to tilt the mash tun to get all the water out?
you could always fill the bottom with something suitable but personally I think if you designed your manifold well then it should get most of the liquid then just maybe tilt at the end to get them last few drops. If you are batch sparging then I wouldnt worry too much about it.
by the time you get the grain in there, you'll lose a few ounces. mine is the same way, but I don't sweat a few drops, since i do batch sparge anyway, so i get the right amount of wort anyway