# Do you trust your watter test kits and why you should not?



## ppaskova (Apr 27, 2010)

Hi Guys

I posted this question before but now I'm little more serious ! And here is why. I have two fish tanks, 10Gl and 30Gl. And today tested water in both with my API Liquid kit and in my 10Gl all the parameters were normal But when I tested my 30GL tank with the same kit here are parameters:

Ammonia - 1ppm
NO2 - 0 ppm
NO2 - 5 ppm
PH - 8.8

10 min after I decided to retest (no changes in the fish tank). Second test:
Ammonia - 0 or close to it
NO2 - 0
NO3 - around 2 ppm or so
PH - 8.8

After that I derided to test with stick test and it showed all the parameters normal And tested PH again with liquid test third time 10 min after (no changes to fish tank)
PH - 7.2
In addition I have Seachem Ammonia and PH alert indicates in my tank that did not show anything abnormal.
So now can anybody explain to me what happened as during all 3 tests I did not make any changes to 30Gl tank or it's water ????


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## Mlevi (Jan 28, 2012)

I always consider those tests as an 'indicator' rather than a precision measurement. Too many variables to make it far from precise. As indicators though, the tests have their place.

Al.


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## pyrrolin (Jan 11, 2012)

maybe you didn't clean the test tubes well enough

didn't fill the tube the exact same amount

didn't hold the bottle straight, giving a slightly different sized drop

waited a slightly different time to check the readings

maybe your very first test that showed the ammonia, a fish pooped right there just before you got a water sample

maybe you had a tiny piece of plant matter in the tube that changed the reading

I use a seringe to get water out of my tanks, I first suck up water into it and then squirt it out and refill to clean it.

I don't think anyone expects test to be 100% dead on, but they are close enough to show any problems.

I don't record my readings, I go by many factors in determining what action if any I will take. Example, last night I tested a bunch of my tanks for nitrates as my DIY co2 was having problems producing co2 and I had just fixed the problem. I found my nitrates were around 20 to 30 and decided to do nothing as I know that with the co2 working again, the plants will suck up some of the nitrates and I don't want nitrates to bottom out like they have in the past


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## ppaskova (Apr 27, 2010)

Interesting. So what should I do in this case if I see that everything looks good in the tank and fish is happy but test showing otherwise ? I guess retest to see if I get consistent results ?


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## pyrrolin (Jan 11, 2012)

yup, retest


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## Jackson (Jan 30, 2009)

I haven't tested my water in a long time. Only time I do is if one of my fish look off or when setting up a new tank

When I do I trust them as long as their a year or so away from expiring


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## ppaskova (Apr 27, 2010)

Jackson said:


> I haven't tested my eater in a long time. Only time I do is if one of my fish look off or when setting up a new tank
> 
> When I do I trust them as long as their a year or so away from expiring


Well my is a brand new kit. 5 years to expiry. Also i do grab my water with the small bottle from the tank and test it then.


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## Jackson (Jan 30, 2009)

ppaskova said:


> Well my is a brand new kit. 5 years to expiry. Also i do grab my water with the small bottle from the tank and test it then.


LoL

This auto correct is horrible

They used to expire much sooner. I wonder what they changed


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## altcharacter (Jan 10, 2011)

API is such a horrible test kit.


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## pyrrolin (Jan 11, 2012)

do you know a better one that is easily available?


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## Darkblade48 (Jan 28, 2008)

As mentioned, there are various causes that may explain why your tests are reading differently each time.

In addition, test kits are meaningless if you do not calibrate them. Phosphate, nitrate, ammonia can all be calibrated using calibration solutions. Technically, so can pH (but can be a little more involved for those that do not have access to a lab).



pyrrolin said:


> do you know a better one that is easily available?


LaMotte makes excellent test kits, albeit slightly on the expensive side.


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## ppaskova (Apr 27, 2010)

Darkblade48 said:


> As mentioned, there are various causes that may explain why your tests are reading differently each time.
> 
> In addition, test kits are meaningless if you do not calibrate them. Phosphate, nitrate, ammonia can all be calibrated using calibration solutions. Technically, so can pH (but can be a little more involved for those that do not have access to a lab).
> 
> LaMotte makes excellent test kits, albeit slightly on the expensive side.


Two questions 
1. How to calibrate a test kit ?
2. Where to buy LaMotte test kits ?


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## Darkblade48 (Jan 28, 2008)

ppaskova said:


> Two questions
> 1. How to calibrate a test kit ?
> 2. Where to buy LaMotte test kits ?


You will have to create a reference solution (with known concentrations of what you are testing for). For example, for my nitrate test kit, I created 40, 20, 10, 5 and 2.5 ppm solutions. From there, using my test kit, I can determine how accurate it is.

For LaMotte test kits, I ordered through the Biology department (now Cells and System Biology) department from University of Toronto.


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## geonut (Jun 24, 2012)

*Test Kits*

Salifert - now has freshwater tests as well as marine.


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