# Warning - API PH Test



## rpadgett37 (Jan 1, 2014)

The API PH test results appear to be inaccurate at 7.2 and above.

This test kit has two PH scales, upper and normal. In the color charts, both tests overlap from 7.4 to 7.6. In my tests, whenever PH measures at 7.2, over 24 hours, the PH measurement climbs to 7.6. Measuring from there into the upper PH range, the color for 7.4 comes in a little lighter than 7.4. In short, combining these results provides for a final combines result / overlap that makes it impossible to determine what the actual PH is.

I read in another thread that using this test and the Nutrafin PH test side by side shows different results. In this area, I have noticed the same thing.

As an example, I have two water test areas, the water in the aquarium and in a separate bucket (5 gallons each, same temperature). In both cases, the starting point was PH 7.6 and KH 20-30 ppm. I added 1/16 teaspoon of acid buffer as directed by the instructions. KH and PH both dropped to PH 6.4-6.6 and KH 0 ppm.

From there, in the aquarium, I added acid and alkaline buffers to each. In the aquarium, I added them at a ratio ratio of 1 acid to 4 alkaline. In the bucket, I added each at a 1 to 2 ratio (suggested ratio to get to a base of PH 7). I was experimenting in non RO tap water with the ratios to see which would get me in the 7.0 - 7.2 range with a KH of around 50 ppm. In short, I was bracketing the buffers as instructed to achieve the base line I wanted prior to adding CO2.

To make a long story short, testing the PH last night with both PH tests, the measurements came in at PH at 7.2 in the aquarium and 6.8 in the bucket for each. I tested again this morning. API showed a PH at 7.6 in both and a little lower than 7.4 on the an the high scale. Nutrafin showed PH results the same as last night, PH 7.2 in the aquarium, PH 6.8 in the bucket.

It is important to mention that KH measurements last night were the same as this morning so that's not the issue.

Won't be using the API any longer, and this calls into question the accuracy of the API Ammonia, Nitrite and Nitrate tests.


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## kittenfish (Dec 1, 2013)

Just curious, what plants are you growing that require knowing the pH with that level of accuracy?

You may want to look into a pH meter, as I don't think these kinds of tests for pH are ever really that accurate.


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## rpadgett37 (Jan 1, 2014)

Well... To be honest, this posting isn't really about wanting to be so perfectly precise for a particular group of plants. Though I do tend towards being as thorough as I can be, given the resources I have available, I am a bit limited in the equipment I can get.

Having said that, like most, I have to rely on these cheap, reasonably accurate products to do my testing. And as I am interested in setting up a reasonably ideal ecosystem for everything in the tank as best I can, I need a product that gives me a consistent, reasonably accurate measurement every time. I honestly don't think that is too much to ask for in something I pay good money for.

Lots of people won't care, which is fine. Some will, hence this post. And for those that do, this may be of interest to them.

Hope I don't sound like a jerk here. If possible, I may just go track down one of those PH meters you spoke of. Probably more than I truly need but it appeals to my perfectionist side 

I never did answer your question, though. I'll be growing various crypts, some Blyxa Japonica and Coral Moss. The crypts I chose should be fine without too much maintenance, but the B. Japonica and Coral Moss will need a little bit extra attention and care.


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