I've been out of town for a couple days, so this is the first chance I'm getting a look at everything. My system is all 1" pipe - some of them are angled into the FT, some are reduced to 3/4", and all seem to work OK.

Here's a pic of how mine are set up - just a U siphon.


Both of the drain lines on these GBs are 1" - the one with media has a 45* angle into the FT, the other has a 90* The only time the siphons will break is when they're completely out of the water.

The water level in the FT fluctuates around 3", the longest the GBs go between cycles is about 15min.