CO2 chart

[Caliban07]

Why don't you use your kh kit to measure the kh of the calibrated solution then compare that to what it states in the instructions?

There may even be discrepancies there.

Also, I'm wondering how the provided solution is calibrated to 4dkh. And what is the starting ph of that solution if you are adding a buffer to RODI. If it has gone through RODI how good is the RODI unit they used and how accurate is the TDS tester they used to test post RODI.

Measure the ph kh and TDS of the provided solution just to see if it is what it says it is?

Maybe you could mix some RODI with baking soda to achieve the same dkh as your tank and use that as the solution to put in the drop checker and then compare against the chart?

I would say stick to one drop checker and just take there reading as a rough guide as to where your co2 levels are at. In theory the drop checker should be close to the chart but there are so many things that could disprove that in practice.

Am I making any sense or just talking jibberish here? lol


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[Delapool]

Well in order to verify the accuracy of the drop checker you would have to read the chart at the same dkh.

The other thing is, the drop checker is using a substance "something blue" can't remember to check ph. It knows that the only influence on ph is carbonic acid and it knows the dkh value (again calibrated at source). Using these 3 it can estimate the ppm of co2.

So you have discrepancies with 2 different measuring methods of ph 1. Your machine 2. The blue substance in the drop checker.

Then you have the accuracy of the premixed solution calibrated at source.

The chart is also a real time value whereas the drop checker is not real time. This creates another host if potential inaccuracies. This bodes the same when measuring c02 of patient expired gas. There are two types of measuring 1. Main stream 2. Side stream. Mainstream is real time because the sensor is located inline with the intubation tube whereas side stream pulls a sample from the main line to a sensor located elsewhere so the information fed back is a) behind and b) is open to all kinds of other factors which may affect readings such as pressure, temperature etc.

Also the drop checker colour indicator has a 10ppm variation between each colour so there is huge room for inaccuracies there too.

When I say inaccuracies I don't mean that the drop checker is a null method, what I mean is, it can't be easily compared to a real time calculation.

At the end of the day without spending probably thousands of pounds we are limited to low end methods of co2 measurements and the drop checker is accurate to whatever the manufacturers specifications are and the user as far as they are concerned should only be interested in the colour. To me your checker is telling you you have high co2 at a dkh of 4 based on the measured ph, another checker could tell you something a little different.





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I think the drop checker at a 4dkh reads 30ppm co2 as a green colour if I'm reading everything right?

I'm ok with a 15 or 20% error or difference but this seems a bit much. Now I'm really confused if I've even set it up correctly. And if it is pre-mixed, does green mean 30ppm as thought? Maybe it actually means 15ppm or 40 ppm - it's really bugging me now and I can't find much on google

Photos of instructions below if this helps. It says don't add water so I assume this implies pre-mixed?

Reading reviews on one link I found the cheery information that half the time it leaked the solution into the tank as well. Now the glass ones are looking much more attractive...

 

[Caliban07]

I don't know what levels green indicate but the dark green colour in the centre of the picture indicates 'proper' co2 levels where as a lime green equals too much and the dark blue is too little. The min/max values for the 'proper' co2 level could vary.

The packet says it all really. "For approximate co2 levels"

I don't know what more to say. Didn't even know what a drop checker was 2 days ago.


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[Delapool]

Why don't you use your kh kit to measure the kh of the calibrated solution then compare that to what it states in the instructions?

There may even be discrepancies there.

Also, I'm wondering how the provided solution is calibrated to 4dkh. And what is the starting ph of that solution if you are adding a buffer to RODI. If it has gone through RODI how good is the RODI unit they used and how accurate is the TDS tester they used to test post RODI.

Measure the ph kh and TDS of the provided solution just to see if it is what it says it is?

Maybe you could mix some RODI with baking soda to achieve the same dkh as your tank and use that as the solution to put in the drop checker and then compare against the chart?

I would say stick to one drop checker and just take there reading as a rough guide as to where your co2 levels are at. In theory the drop checker should be close to the chart but there are so many things that could disprove that in practice.

Am I making any sense or just talking jibberish here? lol


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No, no - makes sense. I'd just like to know what the darn drop checker is telling me. I came across other links where it stayed blue even with co2 injection (in one instance the fish were gasping at surface with too much co2) or did other strange stuff (even allowing for a delay). I'll just email them and ask. Lol - I thought this would be easy.

I don't know if the kh test will work as the liquid is dark blue from the bottle. Will have a look on weekend.

I think I have everything to make the pre-mixed solution from scratch. Will see on the weekend. At least then I could compare as you say. I ordered a few of the drop checkers so could even run them side by side.

 

[Delapool]

I don't know what levels green indicate but the dark green colour in the centre of the picture indicates 'proper' co2 levels where as a lime green equals too much and the dark blue is too little. The min/max values for the 'proper' co2 level could vary.

The packet says it all really. "For approximate co2 levels"

I don't know what more to say. Didn't even know what a drop checker was 2 days ago.


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If the tank wasn't so heavy I'd sell it and get budgerigars....

Edit - will pass on anything that gets emailed back.

 

[Caliban07]

If the tank wasn't so heavy I'd sell it and get budgerigars....

Edit - will pass on anything that gets emailed back.

Yeh let us know what they say. I emailed Hach with a few queries but got nothing. It may be time to phone them


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[Caliban07]

What you need is a an electronic test kit that measures co2 partial pressure. There are so e accurate means of measuring co2 out there but they will probably put a big hole in your wallet.


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[Delapool]

What you need is a an electronic test kit that measures co2 partial pressure. There are so e accurate means of measuring co2 out there but they will probably put a big hole in your wallet.


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So far I've been told nothing useful and asked to contact another company...grrr.

Will see what comes back.

I could just make the solution I guess and go 'old-school'. Probably should do that once. I think I bought 4 boxes so have spare drop checker units.

I wonder if labs test this stuff? Maybe it would be cheaper to take a bottle of tank water in and say I want chemistry plus co2???

 

[Caliban07]

So far I've been told nothing useful and asked to contact another company...grrr.

Will see what comes back.

I could just make the solution I guess and go 'old-school'. Probably should do that once. I think I bought 4 boxes so have spare drop checker units.

I wonder if labs test this stuff? Maybe it would be cheaper to take a bottle of tank water in and say I want chemistry plus co2???

Haha that would be a great idea if possible.

I'll bet some of the labs here in the hospital could provide dissolved c02 readings. I think breweries use meters too for quality testing purposes.

I'm starting to wonder how the solution is calibrated at source. Would it have to be calibrated in a chamber that cannot allow for alterations caused by atmospheric co2 for example. When you take the lid off the solution for the first time does that alter the solution in any way? I don't think that they would be that anal. After all, they have just targeted a niche in the market for churning out drop checkers and since the value is approximate they can get away without worrying about being overly accurate.

What are the more expensive drop checkers like?


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[Mebbid]

The solution is just a 4dkh reference solution with a ph measuring chemical mixed in with it.

 

[Delapool]

The solution is just a 4dkh reference solution with a ph measuring chemical mixed in with it.

It's like the ph chemical for normal ph test? I saw instructions somewhere.

I don't really use the ph kit anymore except for checking so could readily spare some. The 4dkh solution sounded easy (er, just precise).

Still hoping for an email answer tonight.

 

[Delapool]

Haha that would be a great idea if possible.

I'll bet some of the labs here in the hospital could provide dissolved c02 readings. I think breweries use meters too for quality testing purposes.

I'm starting to wonder how the solution is calibrated at source. Would it have to be calibrated in a chamber that cannot allow for alterations caused by atmospheric co2 for example. When you take the lid off the solution for the first time does that alter the solution in any way? I don't think that they would be that anal. After all, they have just targeted a niche in the market for churning out drop checkers and since the value is approximate they can get away without worrying about being overly accurate.

What are the more expensive drop checkers like?


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got to be something.

The wish list had a potassium test kit and a par meter next (calling Santa!).

 

[Mebbid]

It's like the ph chemical for normal ph test? I saw instructions somewhere.

I don't really use the ph kit anymore except for checking so could readily spare some. The 4dkh solution sounded easy (er, just precise).

Still hoping for an email answer tonight.

Yep, remember that ph changes in a measurable amount based on dkh and co2. You can use that co2 chart to check the ph that you want to shoot for and color match it. You would probably have to measure the amount of water in the drop checker and add an equal amount to match the normal testing levels of solution.

The reference solution can be made fairly easily as well. There are directions stickied on the planted tank forum.

 

[Caliban07]

You're never going to get an accurate test without proper machines and apparatus at the end of the day

I mean accurate as in matching the chart.

The drop checkers are really just and indication that something is a miss.

It's worrying that you have read reports on some failing to read high c02 when livestock were gasping.

As mentioned, In marine setups where buffers are part of the habitat and where alkalinity is closely monitored changes in ph do warrant close inspection with particular attention to co2.

Is the drop checker telling us anymore than this approach?


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[Mebbid]

You're never going to get an accurate test without proper machines and apparatus at the end of the day

I mean accurate as in matching the chart.

The drop checkers are really just and indication that something is a miss.

It's worrying that you have read reports on some failing to read high c02 when livestock were gasping.

As mentioned, In marine setups where buffers are part of the habitat and where alkalinity is closely monitored changes in ph do warrant close inspection with particular attention to co2.

Is the drop checker telling us anymore than this approach?


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That "report" is not much more than just a snapshot. We have no way of knowing what was actually happening with the tank. Did the co2 output change suddenly? There's a lag between co2 injection and measurement by the drop checker. Did the solution mix wear out in the drop checker? Was the person using a crappy drop checker? Did the person mix the solution properly? Did the person use 4dkh reference solution? Heck, I've even had a piece of duckweed lodge in my drop checker unexpectedly giving me absolutely no registered co2 readings.

Also, as to "accuracy" we have absolutely no need to have a 100% accurate reading. Just a ballpark figure is more than enough to tell us everything we need to know.

 

[Caliban07]

That "report" is not much more than just a snapshot. We have no way of knowing what was actually happening with the tank. Did the co2 output change suddenly? There's a lag between co2 injection and measurement by the drop checker. Did the solution mix wear out in the drop checker? Was the person using a crappy drop checker? Did the person mix the solution properly? Did the person use 4dkh reference solution? Heck, I've even had a piece of duckweed lodge in my drop checker unexpectedly giving me absolutely no registered co2 readings.

Also, as to "accuracy" we have absolutely no need to have a 100% accurate reading. Just a ballpark figure is more than enough to tell us everything we need to know.

Both true. That's why I'm kind of interested to see how accurate they actually are.

Dela, perhaps we should start a new thread or knock it on the head as "unsolved" lol


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[Delapool]

Both true. That's why I'm kind of interested to see how accurate they actually are.

Dela, perhaps we should start a new thread or knock it on the head as "unsolved" lol


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Yeah, bit more complicated than I thought. I'll report back on anything from emails or testing but will park it as nothing on google.

 

[Delapool]

A update just to report ... Nothing.

The help section is extremely useless. So far I've been told to contact a distributer - tried that and got sent back to supplier. Frankly if the supplier doesn't know...grrr.

Also the supplier finally gave up and gave me the technical details .... For the wrong product.

I've also tried searching the FAQ on the website as well and that has been a washout.

 

[Mebbid]

A update just to report ... Nothing.

The help section is extremely useless. So far I've been told to contact a distributer - tried that and got sent back to supplier. Frankly if the supplier doesn't know...grrr.

Also the supplier finally gave up and gave me the technical details .... For the wrong product.

I've also tried searching the FAQ on the website as well and that has been a washout.

hahaha that's awesome

 

[Delapool]

I can see I will have to go "old school" and make a solution up. Character building....