I've been experimenting with color checking apps under controlled lighting conditions for reading vials. It sucks being colorblind.I found that the simple API test kit works well with Coppersafe - but with one important caveat, I read the results on a custom curve I made for a Hach spectrophotometer - I can't eyeball it at all (grin).
Jay
Even the young eyes in my household can't read test results much better than I can. I rarely get different results from them, but it makes me feel better when they argue over the results.
Australia is just too far for me to drive and borrow your spectrophotometer!