I have attached some pictures I took while building my growbeds stand and the beginnings of my (your) "Bell-Siphon". The design works very well, but it is very difficult to obtain the parts and pieces to construct it properly. A 3" PVC cap will not fit inside of a 4" PVC pipe without some modification.(alot of sanding!), Bulkhead fittings and 1 1/2" to 3/4" reducers are hard to find in a small town! (I got them through http://www.pvcfittings.com)
Thanks again for the help!, you have a Great Blog/site!