I did drill a 3/4″ hole in the PVC, and then I used a 3/4″ steel pipe plug with outside threads as a thread tap. Worked pretty well and didn’t cost nearly as much as a real 3/4″ tap and die set. I try to keep 2″ to 3″ of water in the tubes. The [...]

John, you are correct. The intake port is positioned high, and the outlet low. I did tests during construction to get the position just right. If it drained too fast, then the standing water level would be too low, and conversely, if the outlet was too high, the pipe would fill up and overflow. A [...]

I use a small fountain pump to pump the water up to the top of the system. Here’s a link:
http://www.homedepot.com/h_d1/N-5yc1v/R-202017049/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

It’s a 170-200 GPH pump that can push water up to ~7 feet.

I do cover the reservoir, and in addition I put reflective insulation around it to help deflect direct sun, as it raised the temperature of the water considerably. Even with the reservoir covered, I have to replenish the system roughly once every two weeks. A lot of water is lost through the plants themselves and [...]