How is aquarium coop test strip different APT master test kit?

[martinmin]

I tested the pH values of the same water by both aquarium co-op's test strips and API master test kit, and found that the pH values are quite different. The two values are below: 

Aquarium coop: 6.8

APT test kit: 7.3

Is this normal? 

[Bigmike]

Test strips are generally less accurate than liquid tests. Biggest upside to test strips is they are quick and easy and unless you're trying to breed fish and need very specific parameters, a close ballpark is good enough to let you know if things are stable or if something is way off. 

[Patrick_G]

I've found some discrepancies between my Co-op test strips and the API liquid test. The problems with the liquids is the need to accurately follow the instructions. Drops must be a uniform and accurate size, the correct number of drops must be administered, bottles must be agitated for the required length of time, vials must be clean etc. For day to day use I stick with the strips even though they might not read exactly the same as the API tests. 

[Tommy Vercetti]

None of the test kits available for our hobby are scientific grade and they all have inaccuracies. However, they are still useful because they are accurate enough to keep water parameters in the ranges necessary for this hobby. I use API liquid tests and ACO test strips and have no complaints about either one.

The ACO test strips are faster and easier to use. But when I am wanting to really keep tabs on water parameters then I use the API liquid test, but this requires cleaning the and drying test vials afterwards, which is tedious when compared to ACO test strips.

[Galabar]

I've tried various API tests and references solution and they seem accurate.  The Aquarium Co Op strips always show Ph at the low end (bright orange).  So, I don't think they are actually doing what they are supposed to be doing.

I'm actually using the strips for quick nitrate testing.  So, this isn't a big issue.  However, I would advise against using them for Ph as they don't seem to work (that sounds harsh, but it seems accurate).

Edited May 10, 2023 by Galabar

[martinmin]

When using test strip or liquid tests, what should I read to check whether the tank is lacking nutrients?  For example, how do I know it lacks phosphorus and potassium, or even iron? The nitrate doesn't tell these, right? KH is an indication of co2 level and GH is the general hardness, neither reflects the specific minerals. 

[nabokovfan87]

On 5/7/2023 at 2:22 PM, Patrick_G said:

I've found some discrepancies between my Co-op test strips and the API liquid test.

When it comes to my own experiences... man what a mess.

I initially used the Tetra ones based on Cory's old vlog videos and recommendations.  I was using the API kit prior to that.  When I transitioned to liquid there was some discrepancy.  It wasn't a serious issue at all, but there were and always will be some strips I won't use.  (ironically API is one of the worst offenders for me).

I replaced my tetra strips with the new ACO strips as both my liquid kit and my tetra strips were well expired at this point.  I used the tetra ones as a comparison, knowing that they could be erroneous in quality compared to the fresh ones.  Ultimately, my biggest struggle with the new strips is that I have a very difficult time reading the values. 

In the testing above it was mentioned a very slight shift of 6.8 -> 7.3 with the PH.  I often find myself squinting and changing rooms (light sources) to try to find out what I am looking at.  It might be 6.8, but it just as well could be 7.2.  I squint again and just weight the colors and it's not quite 7.4+ and so I just submit "it's fine and within acceptable ranges".  With the API kit, if you test 7.3 with the "low PH" range then you'd want to right away go and re-test with the high PH kit range to verify your results.

For me:

API Tests:
-Nitrate is a pain
-PH, easy to test but I'm always doing 2 tests because it's in that weird range of 7.0-7.2
-Ammonia is so useful!
-They need to have the GH/KH kit included or purchased and I don't like how difficult the test is.
-Color scale is generally easy to read, just remember to shake the bottles!

ACO Strips:
-Nitrate is hard for me to read (pink is very feint in my range)
-Nitrite is easy to read because if it's not white it's sensitive and obvious
-PH is very hard for me to read
-GH can be very hard for me to read
-KH is often in the 40-60 range and the scale is 40 or 80.  I couldn't tell you what the PPM is but it's "enough"

Here's the thing......

I got the API GH/KH kits and it was vastly off compared to the strips.  So I am right back at the beginning of wanting to play water chemist and forcing myself to use liquid kits.  I have had some tests where I trust the strip more than I trust the liquid.  I like to have both and to verify them off of one another.  If I see ammonia at 0 on one test, but the tank is clearly showing stress signs, I'll verify with the other test kit.

Hopefully that helps.  I would use both. Honestly.  If you have to choose one, get that lab coat out.

[nabokovfan87]

On 5/10/2023 at 9:53 PM, martinmin said:

When using test strip or liquid tests, what should I read to check whether the tank is lacking nutrients?  For example, how do I know it lacks phosphorus and potassium, or even iron? The nitrate doesn't tell these, right? KH is an indication of co2 level and GH is the general hardness, neither reflects the specific minerals. 

https://www.aquariumcoop.com/blogs/aquarium/ph-gh-kh
GH = mixture of calcium, magnesium in the water. (See Equilibrium as it also contains potassium but is a GH buffer)
Phosphate = use the liquid test kits (Aquarium Co-Op does sell it I believe
Iron = use the liquid test kits
Calcium = use the liquid test kits (very, very common in saltwater)
Potassium = use the liquid test kits
Magnesium / Manganese = use the liquid test kits

JBL and Sera have really thorough test kits you can find.  Fritz is also in the process of releasing one.  Seachem and API have a lot of the individual mineral test kits available.