I have been using a SWC Master Doser X3 for around 6-7 months now and really like it. When researching to purchase noticed it looked VERY similar to some much more expensive units out there and had some of the same touted features like the 3-way peristatic pump to eliminate back-siphoning etc... I dose DIY 2-part for Cal, Alk and Mg and have nearly dialed it in to my Corals needs finally.
Cheers, Todd