Yeah I'm in coco also. I found when I adjusted to just a tint of orange 5.5 - 5.8 it worked the best. I used to do 6.0 (Just a little more yellow then your picture) but it seems, at least in my situation, a little lower on the ph scale and let them drink it up for a day or two, as they eat the ph will slowy rise.
Do you use the dropper that comes with it? That weird looking tube that you have to cut the end off of?
Next on my list of equipment is a temperature, ppm, and ph monitor but need to budget the few hundred dollars to get it.
Its lights off now, but tomorrow I'll try and remember to post a picture of what the color I use in my coco plants looks like.