Hanna co2 test not working

[Asher E.]

I got a Hanna co2 test and I can’t get it to work right.
I added 10ml of water to the container, 1 drop of the indicator liquid, the water was still clear, and then I filled the syringe with the solution liquid, put the tip on the syringe, added drops from it into the 10ml of water, and i kept adding drops into the water and gently stirring after every couple drops, and I eventually emptied the syringe and the water still didn’t turn pink.
What could I be doing wrong?
I have fish in the tank that aren't gasping for air so I don’t think there’s more than 50ppm of co2.

 

[Art]

First, check the expiration date on the kit.

Second, are you supplementing CO2?

 

[Asher E.]

First, check the expiration date on the kit.

Second, are you supplementing CO2?

I checked it and it doesn’t expire until next year. And yes, I’m injecting co2. I’ll try the test again now while the co2 is off and I’ll see if I can get it to work.

 

[Naturescapes_Rocco]

what is your KH? I know the test kit is very accurate for low KH, but we haven't had someone in the hobby test with very high KH water before.

Also it's 100% possible you ARE injecting 50+ppm and still have healthy inhabitants if your oxygen levels are really high and you have tolerant species. I had this happen with my Hanna kit, and I thought it was bogus. Then I installed my drop checker and it was the most yellow I've ever seen
Most fish were fine, Amano shrimp were not happy.

What color is your drop checker by the end of day? Compare that with your Hanna kit and you'll have a good idea of what your accurate CO2 reading is.

For what it's worth, my big tank sits at 40ppm CO2 nearly all day. I need to use almost the entire 1mL Hanna titration syringe to get a faint pink.

But I've now been using two different Hanna kits on two tanks. Unless you somehow got a dud (which is possible I guess, but seems very unlikely after my testing) you could be injecting 50+ppm.

You can also try adding two drops of the indicator solution, instead of 1. It will give false early readings, but it'll give you an idea again of how much CO2 you're injecting.

 

[Asher E.]

what is your KH? I know the test kit is very accurate for low KH, but we haven't had someone in the hobby test with very high KH water before.

Also it's 100% possible you ARE injecting 50+ppm and still have healthy inhabitants if your oxygen levels are really high and you have tolerant species. I had this happen with my Hanna kit, and I thought it was bogus. Then I installed my drop checker and it was the most yellow I've ever seen
Most fish were fine, Amano shrimp were not happy.

What color is your drop checker by the end of day? Compare that with your Hanna kit and you'll have a good idea of what your accurate CO2 reading is.

For what it's worth, my big tank sits at 40ppm CO2 nearly all day. I need to use almost the entire 1mL Hanna titration syringe to get a faint pink.

But I've now been using two different Hanna kits on two tanks. Unless you somehow got a dud (which is possible I guess, but seems very unlikely after my testing) you could be injecting 50+ppm.

You can also try adding two drops of the indicator solution, instead of 1. It will give false early readings, but it'll give you an idea again of how much CO2 you're injecting.

I have 0dKH. Right now the co2 is off and the ph is at 6.8, I don’t think it could get above 7 without any kh, and I inject enough co2 to lower the ph to around 5.8, but I don’t have a drop checker.
I will just test the co2 right now while the co2 is off.
Also I realized my ph pen might need calibrated, so if that has inaccurate readings that would explain why it shows I have close to a one point ph drop but the Hanna test shows more.

 

[Asher E.]

Well, I just tried it when the co2 has been off all night. The co2 has been off for about 11 hours now and it’s reading as 22ppm of co2. That seems weird as I have this much surface agitation and the ph pen shows close to 6.8. I’ll test with the api liquid ph test just to check if that shows anything. And if that reading is really different from what the ph pen shows I’ll calibrate it.

 

[Asher E.]

API ph test shows 6.4, so I’ll recalibrate the ph pen and test it again with that.

 

[Naturescapes_Rocco]

If your tank did have upwards of 50ppm CO2 it is still feasible for it to have 22ppm CO2. I have similar surface agitation on my 150p, which has even greater surface area to volume ratio (for more offgassing) and my CO2 doesn't drop below 10 or 15ppm, ever.

If you've seen my thread on Testing Test Kits, you know I don't mess around when it comes to my equipment! And over two different Hanna kits used at least 40-50 times, in 3 different tanks, I have found them to be exceptionally accurate and precise as well. Again, not saying yours couldn't be a dud, but it seems that what you're getting a reading of is very likely what the CO2 content is in ppm in your tank's water.

Unless, how are you using the kit? Are you titrating to the faintest pink, or are you going until it's firmly pink in the vial? Are you giving a light swirl between each drops added?

 

[Asher E.]

If your tank did have upwards of 50ppm CO2 it is still feasible for it to have 22ppm CO2. I have similar surface agitation on my 150p, which has even greater surface area to volume ratio (for more offgassing) and my CO2 doesn't drop below 10 or 15ppm, ever.

If you've seen my thread on Testing Test Kits, you know I don't mess around when it comes to my equipment! And over two different Hanna kits used at least 40-50 times, in 3 different tanks, I have found them to be exceptionally accurate and precise as well. Again, not saying yours couldn't be a dud, but it seems that what you're getting a reading of is very likely what the CO2 content is in ppm in your tank's water.

Unless, how are you using the kit? Are you titrating to the faintest pink, or are you going until it's firmly pink in the vial? Are you giving a light swirl between each drops added?

Thanks. It was as soon as it turned pink. Also I think it probably is over 50ppm if co2 now because I realized my ph pen was pretty off, so I’m trying to recalibrate it.

 

[Asher E.]

I got it working now. I have close to 60ppm of co2 and the fish are totally fine.
I turned it down some because I don’t need that much co2.

 

[BenB]

I just had a similar experience. I put on a new CO2 diffuser this morning. I tested my CO2 when the light came on, and it was off the scale. The syringe goes to 50ppm and the pink was disappearing in just a second of swirling even down to 50. I've cut the CO2 off for an hour and turned the flow down. I'll check it again later. Luckily the pH only got down to 5.5 so I hope everything is OK with the plants.

 

[Naturescapes_Rocco]

I just had a similar experience. I put on a new CO2 diffuser this morning. I tested my CO2 when the light came on, and it was off the scale. The syringe goes to 50ppm and the pink was disappearing in just a second of swirling even down to 50. I've cut the CO2 off for an hour and turned the flow down. I'll check it again later. Luckily the pH only got down to 5.5 so I hope everything is OK with the plants.

Plants will be fine with major pH swings and 50+ ppm CO2, the only concern would be any inhabitants! If they're not gasping at the surface you'll be OK.

 

[BenB]

Plants will be fine with major pH swings and 50+ ppm CO2, the only concern would be any inhabitants! If they're not gasping at the surface you'll be OK.

Excellent! There are no inhabitants, so we are good.

 

[Antonis Koutsouras]

Very interesting discussion about the Hanna test.
In my aquarium, I also see that I probably have around 55 ppm.
What I struggle to understand is how pink the solution should get before I stop adding the reagent.
Should I stop as soon as it turns slightly pink, or only when it becomes fully pink?

 

[BenB]

Should I stop as soon as it turns slightly pink, or only when it becomes fully pink?

I have the LaMotte CO2 kit, but it works the same. My directions say after the solution has stayed pink for 30 seconds.
I will say that right before I consider it final, sometimes it appears there is a pink tint if I look at the glass edges. Sorry, hard to explain.
I consider it done when there is definitely a faint pink shade looking through the middle. I try to hold it up to a piece of paper if I'm not sure. The yellow tint of my bathroom lights can make it tricky if my eyes are tired.

 

[Minninips]

I am also struggling with the "how pink should the solution be". I don't currently have any livestock, so I can't use that as a gauge. My drop checker is pretty much green 24/7. I haven't seen it yellow.

For what it's worth, my big tank sits at 40ppm CO2 nearly all day. I need to use almost the entire 1mL Hanna titration syringe to get a faint pink.

I have tested a few times and I've gotten what I think is 4.5 and another 5.5 of reagent. Following the instructions, with 10 ML of water, it's 4.5 or 5.5 x 50 = 225-275. What am I missing to get the ppm, because 225-275 can't be correct?

 

[Naturescapes_Rocco]

I am also struggling with the "how pink should the solution be". I don't currently have any livestock, so I can't use that as a gauge. My drop checker is pretty much green 24/7. I haven't seen it yellow.

Faint pink. Really, any pink that lasts longer than 20-30 seconds. If you struggle, make sure to have good natural light and a white paper background to check against. I like to add 0.05mL at a time from the 1mL titrant syringe and lightly swirl.

If I swirl and the solution stays a very faint pink for 30 seconds or longer, that's close to the current CO2 level.

I have tested a few times and I've gotten what I think is 4.5 and another 5.5 of reagent. Following the instructions, with 10 ML of water, it's 4.5 or 5.5 x 50 = 225-275. What am I missing to get the ppm, because 225-275 can't be correct?

If your water sample is 10mL, then using 5mL of the titrant would equal 25ppm CO2.
4mL of titrant would equal 20ppm CO2,
8mL of titrant would equal 40ppm CO2.
I think you're just off a decimal point!