jk, You are someone who knows hydraulic theory and likes to calculate the troubleshooting of the issue. I am thinking in a different tack. If things don't make sense, I revert to trial and error methods if it is not too expensive. Here is my $0.02. My opinion may not b e totally accurate but so what. When you open the end of the 1/2" line you drop the pressure for the emitters to near zero and they work. This leads me to believe 20 psi is way to high for your pressure compensating emitters. You, in essence, are doubling regulating the line. Most drip system work at optimum at 10 to 15 psi. So the issue is two different types of drip on the same system. The bubblers don't really care what the pressure is (with in a range) but need flow. The emitters are the opposite. So to get to the point, change the emitters that aren't pressure compensating or reduce pressure to 10 psi with an additional in-line regulator or separate the two types of drip and reduce the emitters to a lower pressure or change them out. Those type are generally called torture-track(that's how they internally regulate pressure) and tend to clog reasonable quickly. With a level area, you don't need that type of emitter. There are many ways to go. So let us know what you tried and if it works out. JMHO Aloha

vj, You can be as specific or as spread out as you like or need with drip. The key is making sure the water spreads out(plumes) enough to get all the root ball. Depends of the emitter type you use. There are many out there. I use emitters on 1/8" tubing coming from a 1/4" lateral for trees and vines. Two or three per tree with variable flow emitters. For herbs and larger areas I use T-Tape on both side of the plants or even circles. I would not water Bougs very much, they don't like much water and unless you want a very large plant,keep them in pots in or above the ground. JMHO Aloha

i dont think trees nor conifer need such ... especially if properly planted and mulched .. most trees prefer a good deep drink .. and then NEAR drying thru the root mass ... when i plant in april ... and properly soak the hole .. and properly mulch .. in high draining sand ... the plants might not seed water until later june ... when the heat really hits.. and the soil starts drying at depth ... say 3 to 6 inches down ... and then no more than once per week.. until the fall cools off the soil ... and we can get back to once per week or month watering ... i discovered how it all worked on MU soil.. inn my MI ... buy using a hand trowel to discover how it all worked in MY garden ... so they really dont need to be on a irrigation .. with constant superficial watering ... but then.. i never gardened in AL ... ken

Checkout Netafim techline EZ, with built in emitters, the tubing is 12mm in diameter (smaller than the 17mm-1/2", but larger than 1/4" so you can run lengths like 250-300 feet from your main line) pressure compensating, self cleaning etc. The narrowness makes it easier to hide and so flexible you can run a loop back for 18" line spacing without adding any connectors. All you need to create a circuit is a single slip connector for the 12MM tubing (which has 1/2inch threads on the other side - use than to connect to your main line); and a single end stop connector.