View Full Version : Errors with test kit?

Bill Nye
09/03/2017, 02:40 PM
I have been using a red sea Alk kit for about a month now and I've liked it as far as its consistency is concerned. I also have a salifert kit that I use to check up on my Red Sea kit every once in a while.

Yesterday I tested my alk using only the Red sea kit and it came to 7.7 which is what my tank always runs at.

Today I tested again and it came to 8.4? My alk has been running steady for a month and a half so I decided to retest using the salifert kit.

The salifert kit came out to 8. In the past I had seen that my salifert kit was usually about .2-3 higher than the red sea kit so at 7.7 on the Red Sea kit it would come to about 8 on the salifert kit.

Is there something wrong with my red sea test kit all of a sudden? I'm confused about the odd reading but everything else seems normal.

09/03/2017, 02:55 PM
Is it expired?

09/03/2017, 05:05 PM
There is no "dry lab" way to answer your question. Here's what I do.

When I obtain a strange result, I test two more times. If the second and third tests are very close to the first, then I am on safer ground saying that the observation was real and I am not wasting my time looking for a problem that was a result of a testing glitch. Comparing one test kit result against another is a good way to get confused.

09/03/2017, 09:38 PM
I agree that a couple of tests might reveal whether the reading was a fluke. Those levels are reasonably close, so the tank should be okay for the time being. Do you know the resolution limit of the Red Sea kit?

Ron Reefman
09/04/2017, 08:09 AM
Was the high reading repeatable with the Red Sea kit?

Do you have a friend or a nearby LFS who can also test your water (take a sample to the LFS)?

Your numbers aren't bad, just different. The test kits we use just are not as good as we would like to believe they are. And human opperator error is so easy to introduce.

09/04/2017, 08:46 AM
Yup, unusual result, repeat test. Human error that we don't realize we are making.

Bill Nye
09/04/2017, 10:05 AM
Thanks for the responses.

Both test kits are fairly new. I just picked up the red sea kit recently and my salifert expires in 2019. Both kits up till yesterday have always gave me consistent results.

I forgot that the salifert kit comes with a control solution. I am going to test my red sea kit against the salifert solution today to see how accurate it is.


Just tested it against the salifert kit and it came out to about 6.7 so pretty close since the reference is supposed to be 6.5 dkH. I just retested my tank and the results are back to normal at 7.8 dkh.

Very strange that it tested twice in a row incorrectly yesterday. I'm glad I didn't fudge with anything and panic.