Yes Myka you're right, sorry, it would appear that more coffee is needed this morning
I actually found that the lower concentrations were easier to read but anything above say 325 or so was extremely difficult. Eventually I just aimed for a cloudy enough solution to obscure the 400 level and figured I was good to go.
I actually find that the zeo PIF supplement lasts quite awhile for the price, it only takes a couple of drops a day to maintain NSW levels. Then again, there may be something else out there that gets the job done for cheaper.