Yes 100% coco. It looks dry on the top but it's damp underneath. I also might have still been getting the blumat dialed in with the one in the picture. I can't remember. As for no runoff, I just run low ec, don't dump a bunch of additives into the mix, and start tapering down about mid flower. I'm just running 1/4 strength at harvest time. I don't flush. Weed turns out fine. If you run high ec and a bunch of additives the outcome might be different. But for that matter the same goes for any medium/method of growing. Many people just use too high of ec and unnecessary additives.
Blumats keep the moisture level perfect in 100% coco when set properly. Not soaking wet, not dry, but good and damp. Root growth is great. Even when I hand watered coco I wouldn't necessarily water everyday. I would let it dry out some. I noticed better root growth when I didn't drench it everyday. 100% coco doesn't dry out as fast as coco/perlite. The trick is keeping it at the right level of moisture and blumats do that. I gave up the daily water until runoff a long time ago. If the coco is still good and wet then you don't need to water anymore until it dries out some. Many will disagree but that's how I have been doing things for a long time and all I grow is healthy plants.