What size ag pipe would people recommend.

I have some 100mm stuff around but it means a lot more digging to put it in, I am also going to have troubles trying to get a nice clean fall /slop on the ag pipe. We have had light rain in the last couple days however and I dont see any water buildup except for the corner where my down pipe has been removed.

Should I lay the concrete slap for the patio then put the ag pipe and sleepers on top? or should I try for the ag pipe to be below the slap level hence allowing for drainage below the slap level. The patio slap will be 75mm lower than the house slap.

In the far corner I am down to rock so have been jack hamming it up with an orzito hammer drill, the slow an painful way. From this way I will back fill probably only 100 to 150 mm behind the sleepers with gravel.

I also see the socked vs unsocked ag pipe debate rages on.