Calcium test results from AWT -- HELP!
- Thread starter Goodwin9
- Start date
HBtank
Premium Member
People are putting a lot of stock into AWT. How much do we really know about them?
I find it odd they feel comfortable giving results for ammonia, nitrite, nitrate and phosphate.... with the methods they use.
It is pretty standard that the hold times on these analytes is less than 48-hours and during that 48 hour period the samples must be chilled below 4 degrees celsius, and in at least one case ALSO preserved by H2SO4 for the duration of that period.
I found it odd they have zero standards for sample preservation.. Especially with water that could easily contain organic material like detrius etc.. "just send it in by mail and we will get it in 2-3 days"...
I have seen some odd numbers for these coming back, even on freshly mised RO/DI saltwater.. etc.
Anyways, I just think people see the word "lab" and think it is infalible, without knowing much about them and their methods.
I work with state certified labs every day, and even in a very strict industry have run a cross a few that were, how can I say, less than impressive.
I would like to see some test blanks from them and verification of this lab with another.
I might check into doing that myself.
JMO
I find it odd they feel comfortable giving results for ammonia, nitrite, nitrate and phosphate.... with the methods they use.
It is pretty standard that the hold times on these analytes is less than 48-hours and during that 48 hour period the samples must be chilled below 4 degrees celsius, and in at least one case ALSO preserved by H2SO4 for the duration of that period.
I found it odd they have zero standards for sample preservation.. Especially with water that could easily contain organic material like detrius etc.. "just send it in by mail and we will get it in 2-3 days"...
I have seen some odd numbers for these coming back, even on freshly mised RO/DI saltwater.. etc.
Anyways, I just think people see the word "lab" and think it is infalible, without knowing much about them and their methods.
I work with state certified labs every day, and even in a very strict industry have run a cross a few that were, how can I say, less than impressive.
I would like to see some test blanks from them and verification of this lab with another.
I might check into doing that myself.
JMO
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Goodwin9
Premium Member
I sent off water samples from my 470 g tank and got the results this evening. CA is high on this report. I checked the CA before I sent the sample off and got a reading on 420 using the same Salifert kit I used in testing the 600. One sample comes back 150 points lower than my result and the next results come back 50 points higher than my results. I'm not sure what to think????
I think it just show you how far off these hobby tests kits are.
http://www.reefcentral.com/forums/showthread.php?s=&threadid=1180164
In regards to equipment in use for the aquarium water testing, here is what I gathered this morning.
Hach DR series Spectrophotometers and AutoTitrators
Denver Instrument 200 series meters
Jennco & Denver Instrument Ion Specific Probes
All equipment is tested against reference solutions on a weekly basis and re-calibrated as is necessary. In the case of parameters checked by the Spectrophotometers, the unit is additionally zeroed out before each test with a sample of your water.
We do not sell or share our client list, as I'm sure you both understand and appreciate. This is a relatively new service but I can tell you that we now serve a fair cross-section of hobyists whom have sited a variety of reasons for signing up. Some use our analysis to benchmark their own testing efforts, some use it to establish and verify maintenance and dosing routines, and some see it as an insurance policy.
The collection process is rather simple, just fill the bottles with your water, close it tightly and drop it in the mail...we get it in 2 days and test it immediately. You mentioned in your question the effect of die-off shifting the accuracy of the ammonia during transit. Let me share with you the answer to this quesiton as passed on to me by a staff marine biologist here at AWT:
As far as ammonia in the sample is concerned, it is true that any organisms in the sample bottles that are collected, should they die in transit, would contribute ammonia to the sample. However, there are a few things to consider here. First, the home ammonia test that you are likely currently using, if it is a high quality test kit, reads in increments of 0.1ppm. The equipment that we are using is 1000 times as accurate, but the acceptable range for ammonia is up to 0.05mg/L. What this means is that while your test kit may read zero, you could actually be anywhere from zero up to around 0.08. This is an example of the limitations of home test kits. Given that our equipment is considerably more sensitive, it will almost always find some ammonia in any sample, but unless the water sample you pulled came from the interstitial spaces in your substrate, or contained such an enormous amount of bacteria that your water is cloudy, the ammonia reading will still be within acceptable parameters, and the effect of die-off during shipping could be “waved-off†as negligible. The results that you get would still be 100 to 1000 times as accurate as a home test kit.
Please understand that were we looking at this service from an aquatic toxicology paradigm, there would be an extensive amount of sample preparation, including micron filtration, acid Ph fixation, and sample refrigeration. This kind of service would be extremely cost prohibitive for regular testing. This is not what we are providing. We are providing a level of water analysis that is considerably more accurate than what is available to hobbyists using home test kits, recognizing that the margin for error will still leave the testing results considerably more precise that what you get at home, while maintaining a price point that is within the range of the serious hobbyist.
I hope this helps Dave and please let me know if anything needs more clarification or if any other questions come up as you share this with your group.
Thanks again for your time considering and discussing our service!
Jeremy Redmond
Customer Service
AquariumWaterTesting.com
You should check out the big thread about the AWt service where they went into detail about the testing. There was also discussion about the changes in water chem from shipping.
http://www.reefcentral.com/forums/showthread.php?s=&threadid=1180164
In regards to equipment in use for the aquarium water testing, here is what I gathered this morning.
Hach DR series Spectrophotometers and AutoTitrators
Denver Instrument 200 series meters
Jennco & Denver Instrument Ion Specific Probes
All equipment is tested against reference solutions on a weekly basis and re-calibrated as is necessary. In the case of parameters checked by the Spectrophotometers, the unit is additionally zeroed out before each test with a sample of your water.
We do not sell or share our client list, as I'm sure you both understand and appreciate. This is a relatively new service but I can tell you that we now serve a fair cross-section of hobyists whom have sited a variety of reasons for signing up. Some use our analysis to benchmark their own testing efforts, some use it to establish and verify maintenance and dosing routines, and some see it as an insurance policy.
The collection process is rather simple, just fill the bottles with your water, close it tightly and drop it in the mail...we get it in 2 days and test it immediately. You mentioned in your question the effect of die-off shifting the accuracy of the ammonia during transit. Let me share with you the answer to this quesiton as passed on to me by a staff marine biologist here at AWT:
As far as ammonia in the sample is concerned, it is true that any organisms in the sample bottles that are collected, should they die in transit, would contribute ammonia to the sample. However, there are a few things to consider here. First, the home ammonia test that you are likely currently using, if it is a high quality test kit, reads in increments of 0.1ppm. The equipment that we are using is 1000 times as accurate, but the acceptable range for ammonia is up to 0.05mg/L. What this means is that while your test kit may read zero, you could actually be anywhere from zero up to around 0.08. This is an example of the limitations of home test kits. Given that our equipment is considerably more sensitive, it will almost always find some ammonia in any sample, but unless the water sample you pulled came from the interstitial spaces in your substrate, or contained such an enormous amount of bacteria that your water is cloudy, the ammonia reading will still be within acceptable parameters, and the effect of die-off during shipping could be “waved-off†as negligible. The results that you get would still be 100 to 1000 times as accurate as a home test kit.
Please understand that were we looking at this service from an aquatic toxicology paradigm, there would be an extensive amount of sample preparation, including micron filtration, acid Ph fixation, and sample refrigeration. This kind of service would be extremely cost prohibitive for regular testing. This is not what we are providing. We are providing a level of water analysis that is considerably more accurate than what is available to hobbyists using home test kits, recognizing that the margin for error will still leave the testing results considerably more precise that what you get at home, while maintaining a price point that is within the range of the serious hobbyist.
I hope this helps Dave and please let me know if anything needs more clarification or if any other questions come up as you share this with your group.
Thanks again for your time considering and discussing our service!
Jeremy Redmond
Customer Service
AquariumWaterTesting.com
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Goodwin9
Premium Member
I'm not ready to put my stock in AWT, but I sure would like too. Personally, I would like to throw away some of my odd ball test kits for tests I seem to have a hard time reading and understanding the results. I was hoping that their results would se some where near my results for the same tests that I feel confident in doing myself, if they did, I would buy stock in the company, but the CA result was just too far off for my liking. Two other people tested the same water with different test kits and came closer to mine than AWT. My third set of results from another tank should arrive tomorrow night, so I will wait and see how close those are to my tests.
Someone might ask them how they handle the samples themselves. For example, using an ISE to check calcium might be a very accurate approach, but if the sample isn't treated to undo any precipitation, the results could vary from what the test kit reports. The same issue holds for alkalinity tests.
For ammonia, I wouldn't necessarily worry only about ammonia going up. It might drop, though, depending on a lot of factors. The same goes for the nitrite, nitrate, and phosphate tests, as has been posted previously.
I'm not sure that I necessarily trust their numbers any more than I trust my test kits yet. I definitely trust my pH readings far more than theirs.
I don't see how they can provide a useful measure of that parameter.
For ammonia, I wouldn't necessarily worry only about ammonia going up. It might drop, though, depending on a lot of factors. The same goes for the nitrite, nitrate, and phosphate tests, as has been posted previously.
I'm not sure that I necessarily trust their numbers any more than I trust my test kits yet. I definitely trust my pH readings far more than theirs.
I don't see how they can provide a useful measure of that parameter.
reef_doug
Premium Member
<a href=showthread.php?s=&postid=11046908#post11046908 target=_blank>Originally posted</a> by bertoni
I'm not sure that I necessarily trust their numbers any more than I trust my test kits yet. I definitely trust my pH readings far more than theirs.
FYI... AWT does not test for pH or Salinity. Below is an exert from the aquariumwatertesting.com FAQ tab:
Why don't you test for PH?
pH is the only parameter of significant interest that is not included in our panel because it is subject to change between your house and our lab. pH is also one of the few key parameters that can be tested at home quite easily with sufficient accuracy. pH pens and other electronic pH probe and meter sets are a great way to monitor pH.
Why don't you test for Salinity?
Salinity is easily and accurately measured at home with a good refractometer. We believe that because refractometers are so widely in use and of sufficient accuracy that there would not be enough benefit to justify the additional cost.
----
HBtank
Premium Member
Hmmm...
Sorry but if you read closely all that jargon added up to:
"We can test your unpreserved sample 100 -1000 times more accurately than your home test kits."
Unpreserved = inaccurate for many parameters. How accurate is a very accurately tested, inaccurate sample.. lol... tongue twister
They even say, that as long as ammonia is "within acceptable parameters", that is all you should look at.. They sate you should just "waive off" the the number they give you as incorrect... err I mean "negligible" due to the lack of preservation.
I see people presenting this number in particular as an "exact" measurement of ammonia in their tanks.
Others have even brought up precipitation issues with other parameters...
I think I will send a sample in, and see how it compares to my Hanna photometer for P04 as a reference, as people are getting weird numbers for this, even of freshly mixed SW. At least people seem to have "faith" in it as a home kit.
I personally think the LaMotte and Hach test kits many use, or the Hanna photometers do not fall into their 100-1000 times less than accurate category by a long shot, anyway. Even Salifert.. If they are going against AP on copper testing, well then ok...
These are very reputable testing companies, with accuracy YOU CAN TRUST, and I think a fresh sample may far outweigh the fact ATW owns a multiparameter photometer, an autotitrator and some probes..
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Goodwin9
Premium Member
I received an email from AWT further explaining the discrepancy between my CA readings and theirs...
Hello Chuck,
Sorry for the delay in responding to the potential causes of the difference between the Calcium tests. Below is the meat of the response I got today from our lead biologist:
We found out from Hach that the calcium titration test that hobbyists use is a "dumbed-down" version of Hach's Total Sequential Hardness test version 8329. This test actually measures calcium carbonate. Basically, you take the amount of titrant required to produce the color change from pink to blue, multiply that number by a "digit multiplier" to account for the
expected concentration,(the higher the expected concentration, the higher the multiplier) and the resulting number is the hardness in ppm of calcium carbonate. You must then convert the result to calcium ion. This is done by dividing the molecular weight of calcium, (40.078 g/mole) by the molecular weight of calcium carbonate,(100.08 g/mole) the resulting value is 0.4, which is the percentage of calcium ion found in calcium carbonate. So, if you found that you had 400 ppm of calcium carbonate, you would only have 160 ppm of calcium ion. (400 x 0.4 = 160) In the chart they give you in the Salifert test, these calculations have been pre-prepared for you, but are based on some obvious assumptions. The Hach test goes on to isolate magnesium from calcium hardness. As you can see, any variation that occurs
early on in the calculation is amplified greatly by the later steps. This also doesn't include the possibility of a problem with the
test kit reagents themselves. For example, if the EDTA titrant is slightly too strong, you will get an artificially low result and visa versa. The other reagents, (potassium hydroxide, etc) could also produce skewed results.
Please note, if the reagents are the culprit here, it would not be the first time Salifert had put out a bad batch of kits. Last time it was magnesium, and note how close those two elements are to each other. Not only are they next to each other on the Periodic chart, and carry the same charge, but you can test for both at the same time using the Hach procedure.
I hope that this helps Chuck, please let me know.
Jeremy Redmond
AquariumWaterTesting.com
Hello Chuck,
Sorry for the delay in responding to the potential causes of the difference between the Calcium tests. Below is the meat of the response I got today from our lead biologist:
We found out from Hach that the calcium titration test that hobbyists use is a "dumbed-down" version of Hach's Total Sequential Hardness test version 8329. This test actually measures calcium carbonate. Basically, you take the amount of titrant required to produce the color change from pink to blue, multiply that number by a "digit multiplier" to account for the
expected concentration,(the higher the expected concentration, the higher the multiplier) and the resulting number is the hardness in ppm of calcium carbonate. You must then convert the result to calcium ion. This is done by dividing the molecular weight of calcium, (40.078 g/mole) by the molecular weight of calcium carbonate,(100.08 g/mole) the resulting value is 0.4, which is the percentage of calcium ion found in calcium carbonate. So, if you found that you had 400 ppm of calcium carbonate, you would only have 160 ppm of calcium ion. (400 x 0.4 = 160) In the chart they give you in the Salifert test, these calculations have been pre-prepared for you, but are based on some obvious assumptions. The Hach test goes on to isolate magnesium from calcium hardness. As you can see, any variation that occurs
early on in the calculation is amplified greatly by the later steps. This also doesn't include the possibility of a problem with the
test kit reagents themselves. For example, if the EDTA titrant is slightly too strong, you will get an artificially low result and visa versa. The other reagents, (potassium hydroxide, etc) could also produce skewed results.
Please note, if the reagents are the culprit here, it would not be the first time Salifert had put out a bad batch of kits. Last time it was magnesium, and note how close those two elements are to each other. Not only are they next to each other on the Periodic chart, and carry the same charge, but you can test for both at the same time using the Hach procedure.
I hope that this helps Chuck, please let me know.
Jeremy Redmond
AquariumWaterTesting.com
About phosphate: their test might be total phosphorus. The Salifert kit includes only orthophosphate and not organic phosphorus.
I don't understand the comments from AWT about calcium testing. I don't think he understands how the calcium kit works. I'd still be interested in knowing exactly how they treat the samples, if I were using their services.
I don't understand the comments from AWT about calcium testing. I don't think he understands how the calcium kit works. I'd still be interested in knowing exactly how they treat the samples, if I were using their services.
Goodwin9
Premium Member
I checked my phosphates using the Hanna photomter prior to send off the water sample to AWT and had a reading of .08, AWT's test results were .14 The second sample I sent from another tank tested with the Hanna at .31, and AWT's results came back .35
I am just as confused on the calcium tests?????
Ralph ATL
Formerly mysterybox
The test kits that most people use are $5.00 to $25.00 range. These kits are supposed to give us a "fairly" accurate reading. There will alwats be a +/- of whatever. The +/- is what differs between tests, persons, kits, etc. Salifert, API, & the like do not test phosphates low enough to give you a result below blah, blah, blah. Only Hach, DD Merk, & maybe colormeter are decent enough kits for the under a hundred buck range. Your expectations are too high (which is great, because it's causing the manufacturers to make better test kits). You are doing lab tests at home with massed produced kits that are only supposed to be +/- like 8% to 15% accurate. Do you know how many variables there are in home testing kits?
I also use AWT, and I have found that they verified most of my kits sufficiently. I use DD Merk to measure phosphates after giving up on API (cost me hundreds of dollars in lost corals, imo), Salifert, etc. I verified it against hach. It matched. The AWT puts my phosphates slightly above my own results. Calcium matched with my Salifert kit as did alk (once I had their reference kit, however). Mag, trates, all matched close enough. Do I trust them 100%? NO! But it is one more TOOL that I can use to keep me going forward in the right direction.
Ralph
I also use AWT, and I have found that they verified most of my kits sufficiently. I use DD Merk to measure phosphates after giving up on API (cost me hundreds of dollars in lost corals, imo), Salifert, etc. I verified it against hach. It matched. The AWT puts my phosphates slightly above my own results. Calcium matched with my Salifert kit as did alk (once I had their reference kit, however). Mag, trates, all matched close enough. Do I trust them 100%? NO! But it is one more TOOL that I can use to keep me going forward in the right direction.
Ralph
Goodwin9
Premium Member
I just got the test results back from AWT for my 210 gallon tank. Prior to sending off the samples, I tested phosphates with a Hanna photometer and got a reading of 1.69. AWT's results were 1.66. You can't get much closer. CA was again another story, I tested 420 using Salifert and AWT came back with a reading of 527.
One of AWT's results was 140 points lower than mine, one was 57 points higher than mine and this last one was 100 points higher. I don't know what to think about this one???? How can they be so different??
One of AWT's results was 140 points lower than mine, one was 57 points higher than mine and this last one was 100 points higher. I don't know what to think about this one???? How can they be so different??
