I havent yet bought the 4dkh solution, i'm trying to find out if my API pH indicator is ok, or if i should buy the nutrafin one at the same time.

Not sure on the colour, will check it later

API indicator solution is bromothymol blue, which is what is needed for the drop checker. As far as I can find out, all of the indicator solutions for pH that have a color chart ranging from yellow at about pH = 6 to blue at about pH = 7.2 are bromothymol blue, and will work fine in a drop checker. There is no other indicator dye that gives the yellow to blue colors in the range of interest.

Hi all
Got the solution yesterday and been using the Nutrafin low range ph test solution which seems to work great.
Keith