MIne is like this one
4" pvc works great. I will try to go thru everything for you, This will be the newer design
4"pvc pipe 2lf
flat style cap (glue on)
screw on cap and adapter
50lf pre coiled airhose
fountain pump
1/4" barbed hose to 1/2 mpt adapter
1/2" npt extension
1/2" thread union
6lf 1/4 pex tubing
1/4 pex valve
6lf 3/8 pex tubing
1/4 pex to 1/2 mpt adapter
3/8 pex to 1/2 mpt adapter
I used 1/2 because I already had the taps
drill center of cap and tap
install 1/4 adapter
drill thru side of screw cap adapter and pipe after it is glued and tap
install extension with glue or silicon
install 3/8 adapter on extension
install 1/2" union and barbed fitting to inside of extension
Follow instructions for interior part.
I am getting ready to build another one, I can take some pics and post them up for you.