What's The Best Way To Read Api Test Results?


HI all. Until I bought my kH kit, I thought you just went to a well lit (preferably sunlight to avoid any coloured light interference) area and read the colour of the tube side on, comparing with the chart.

The kH kit says "if you have trouble determining the colour, uncap the tube and look straight down with the tube over a white background."

So I started doing that for the other tests...

The reason I ask is my high pH test is totally different depending on whether you look side on or straight down (same with ammonia). Side on, my hospital tank pH is 7.4. Straight down, it's 7.8. The colours match exactly with each method...

I've been using the "worst" result to play it safe (especially for ammonia), but I'm curious what others do.


I read mine side on, if I can't distinguish which colour the KH or GH is I hold a small LED torch up to the tube and if there is the slightest colour change I call it

The ammonia, nitrate etc seems easier to read to me and I just read them in a well lit room like you

Kellie Lanchbury

Man I want someone to invent a digital readout machine for all water tests, it drives me crazy trying to tell the difference in colors!!!!


I agree with all of you how hard it it to read. Instructions for ammonia, nitrites , and nitrates (they are the hardest to correctly read) say to hold it up in light placing the test tube to the white strip next to the specific test.

The test Is meant to give you an idea. Not an exact number. Most of the time it will alert you to a problem. Being off from 0 just slightly in ammonia or nitrates being somewhere around 10 to 20 will not be a problem. It is a little harder to tell if it is 20 or 40 sometimes with nitrates.

All in all it does a good job. Not perfect.


They have digital pH meters that you can use. I have one

As far as reading your pH. There isn’t much difference between 7.6 and 7.8. So I wouldn’t worry too much about it being exact.

If your high pH is reading 7.4, that is the default reading. It means that your pH is below 7.8. The high pH only reads values of 7.8 and above.

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