I went with Phobya fittings when I was buyiing parts for 2 loops because I needed a lot of fittings and they were cheaper than the others available. I got the first loop assembled, and for the second loop I incorporated some Koolance QD3s. Working with the Phobya fittings sucked - it takes a feat of strength to get the collar down far enough to start on the threads, and then it takes 2 wrenches to get the collar tightened down. With the QD3s, everything just fit together and I was able to tighten them by hand. What are some good compression fittings for soft tubing (3/8"ID, 1/2"OD) that don't resist going together?