Who do you trust?
- Thread starter igadget56
- Start date
HighlandReefer
Team RC
Scientists continue to improve their methods as we speak regarding measuring seawater parameters. There are debates among scientists as to which method is most accurate. This is with using $500,000.00+ lab setups. 
Hobby grade kits are useful as a gage & are not as accurate as we would like. After all, with these kits, the measuring devices......etc are very crude compared to techniques used in chemistry lab. They are usually accurate enough if you shoot for the middle of the recommended ranges. Seawater presents real challenges for test kit manufacturers. Without proper seawater standards to check test kits against, one can not know which kit is the most accurate.
That said, all the results you have found using these three kits work for me, since I don't believe a 1 dKH difference in a reef tank is worth worrying about. Perhaps all three are not accurate to the true level & perhaps the real value is higher or lower.
Hobby grade kits are useful as a gage & are not as accurate as we would like. After all, with these kits, the measuring devices......etc are very crude compared to techniques used in chemistry lab. They are usually accurate enough if you shoot for the middle of the recommended ranges. Seawater presents real challenges for test kit manufacturers. Without proper seawater standards to check test kits against, one can not know which kit is the most accurate.
That said, all the results you have found using these three kits work for me, since I don't believe a 1 dKH difference in a reef tank is worth worrying about. Perhaps all three are not accurate to the true level & perhaps the real value is higher or lower.
HighlandReefer
Team RC
I believe the LaMotte alk kit may be a fresh water alk kit which will read about 10% lower when used in saltwater, which would bring its true reading up to around 8.9 dKH which is the same as Salifert.
This makes your three kits very close IMHO.
This makes your three kits very close IMHO.
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HighlandReefer
Team RC
The Salifert and Hanna are designed for saltwater.
FWIW, alk kits can not be accurate in both freshwater and seawater, so if the manufacturer claims that it can, one may suspect that it is a freshwater kit in many cases.
FWIW, alk kits can not be accurate in both freshwater and seawater, so if the manufacturer claims that it can, one may suspect that it is a freshwater kit in many cases.
igadget56
Member
Highlandreefer.
I believe what you say makes sense.
Most LaMotte are fresh and salt. Wish I knew that before.
http://lamotte.com/aquarium_fish_farming/product_line/individual_test_kits.html
I believe what you say makes sense.
Most LaMotte are fresh and salt. Wish I knew that before.
http://lamotte.com/aquarium_fish_farming/product_line/individual_test_kits.html
igadget56
Member
Highlandreefer.
I believe what you say makes sense.
Most LaMotte are fresh and salt. Wish I knew that before.
http://lamotte.com/aquarium_fish_farming/product_line/individual_test_kits.html
Oh Crap
I believe what you say makes sense.
Most LaMotte are fresh and salt. Wish I knew that before.
http://lamotte.com/aquarium_fish_farming/product_line/individual_test_kits.html
Oh Crap
HighlandReefer
Team RC
:lol:
If you are really into accuracy, perhaps you can try this method for testing alk:
You can buy 0.1 N Sulfuric acid standard used as the titrant from: (you simply substitute the 0.1 N sulfuric acid for the 0.1 N hydrochloric acid with the same results)
Buying 0.1 N HCL can be difficult since there are shipping & other restrictions placed on it by most companies.
0.1 N sulfuric acid standard
http://www.grainger.com/Grainger/it...est Instruments-_-Laboratory Supplies-_-4YNA6
If you own a business, you can purchase 0.1 N HCL from here. You will need to setup an account and the HCL will have to be shipped to your business. Any busines qualifies:
Lab Safety Supply
http://www.labsafety.com/Hydrochlor...150/?ci_src=14110944&ci_sku=146466&CID=9PP001
It would be best to calibrate your pH meter using a 4 & 7 standard before you start the test. The pH test kits are not accurate enough for this procedure.
Easy part; Testing
Now take a sample of your aquarium water, you can use any volume but I like to use 100ml because my pH meter sits nicely in the cup without me holding it at this level. Stick in your pH meter to your sample. You should get the same reading you do when you stick it directly in your tank. If not start over with a clean sample container. Now draw up some 0.1 N HCl solution in to your 5ml syringe. And start dropping into your sample 0.5 mls at a time and watch your pH meter. You are adding a strong acid so your pH should fall rapidly. Once your pH hits 5 start to slow down and add a drop at a time until your pH hits 4.2 . The reason we are shooting for 4.2 is because this is the point where all available carbonates have been converted to carbonic acid. You would think this would be pH 7 but it's not as carbonic acid is a weak acid and you have to really saturate it etc. Anyway, once you have reached pH 4.2 you are done and now can calculate your total alkalinity.
Alk mg of CaC03 /L = A x N x 50,000 / mL of sample
Where A = ml of acid added
N = normality of your HCL
So if you added 4ml of 0.1 HCL before you hit a pH of 4.2
4*0.1*50,000 / 100 = 200 ppm CaC03 equivalents or your total alkalinity is 4 meg/L (mg/L / 50 = meg/L) or 11.2 dKH.
The above information was taken and corrected from this thread:
http://www.reefcentral.com/forums/showthread.php?t=1583884&highlight=acid+titration+alkalinity
Randy provides further details in this article:
What is Alkalinity
http://www.advancedaquarist.com/2002/2/chemistry
For converting ppm calcium equivalent to dKH or meq/L you can use this calculator:
http://www.saltyzoo.com/SaltyCalcs/AlkConv.php
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Disclaimer provided by Disc1:
One disclaimer I would stick on the instructions would be that it's 0.1 N (N as in Nancy it stands for Normal) and not 0.1M (M as in Mary it stands for Molar).
For HCl, a monoprotic acid, the two are one and the same.
For Sulfuric acid, a diprotic acid, 0.1N is 0.05M
For those not initiated in the world of chemistry that may be confusing when you are looking for supplies. Too many people will tell you that Normality and Molarity are the same thing.
If you are really into accuracy, perhaps you can try this method for testing alk:
You can buy 0.1 N Sulfuric acid standard used as the titrant from: (you simply substitute the 0.1 N sulfuric acid for the 0.1 N hydrochloric acid with the same results)
Buying 0.1 N HCL can be difficult since there are shipping & other restrictions placed on it by most companies.
0.1 N sulfuric acid standard
http://www.grainger.com/Grainger/it...est Instruments-_-Laboratory Supplies-_-4YNA6
If you own a business, you can purchase 0.1 N HCL from here. You will need to setup an account and the HCL will have to be shipped to your business. Any busines qualifies:
Lab Safety Supply
http://www.labsafety.com/Hydrochlor...150/?ci_src=14110944&ci_sku=146466&CID=9PP001
It would be best to calibrate your pH meter using a 4 & 7 standard before you start the test. The pH test kits are not accurate enough for this procedure.
Easy part; Testing
Now take a sample of your aquarium water, you can use any volume but I like to use 100ml because my pH meter sits nicely in the cup without me holding it at this level. Stick in your pH meter to your sample. You should get the same reading you do when you stick it directly in your tank. If not start over with a clean sample container. Now draw up some 0.1 N HCl solution in to your 5ml syringe. And start dropping into your sample 0.5 mls at a time and watch your pH meter. You are adding a strong acid so your pH should fall rapidly. Once your pH hits 5 start to slow down and add a drop at a time until your pH hits 4.2 . The reason we are shooting for 4.2 is because this is the point where all available carbonates have been converted to carbonic acid. You would think this would be pH 7 but it's not as carbonic acid is a weak acid and you have to really saturate it etc. Anyway, once you have reached pH 4.2 you are done and now can calculate your total alkalinity.
Alk mg of CaC03 /L = A x N x 50,000 / mL of sample
Where A = ml of acid added
N = normality of your HCL
So if you added 4ml of 0.1 HCL before you hit a pH of 4.2
4*0.1*50,000 / 100 = 200 ppm CaC03 equivalents or your total alkalinity is 4 meg/L (mg/L / 50 = meg/L) or 11.2 dKH.
The above information was taken and corrected from this thread:
http://www.reefcentral.com/forums/showthread.php?t=1583884&highlight=acid+titration+alkalinity
Randy provides further details in this article:
What is Alkalinity
http://www.advancedaquarist.com/2002/2/chemistry
For converting ppm calcium equivalent to dKH or meq/L you can use this calculator:
http://www.saltyzoo.com/SaltyCalcs/AlkConv.php
---------------------------------------------------------------------------------------------------------------------
Disclaimer provided by Disc1:
One disclaimer I would stick on the instructions would be that it's 0.1 N (N as in Nancy it stands for Normal) and not 0.1M (M as in Mary it stands for Molar).
For HCl, a monoprotic acid, the two are one and the same.
For Sulfuric acid, a diprotic acid, 0.1N is 0.05M
For those not initiated in the world of chemistry that may be confusing when you are looking for supplies. Too many people will tell you that Normality and Molarity are the same thing.
HighlandReefer
Team RC
FWIW, in freshwater you titrate down to a pH of 4.5 (not 4.2 as in saltwater) & this difference causes the approx. 10% difference between the freshwater and marine alk kits.
In the case of the hobby grade kits the dyes used change at the appropriate pH level when the titration is completed. Using a pH meter rather than dyes is more accurate.
In the case of the hobby grade kits the dyes used change at the appropriate pH level when the titration is completed. Using a pH meter rather than dyes is more accurate.
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+1 to Hanna and Salifert being relatively consistent and identical. I do, however, find the Hanna a bit easier and faster (although I replaced their [profanity] syrine with a 1cc insulin syringe which is easier to dose well and wastes less solution).
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FWIW, proper use of a syringe in this manner will have an air bubble in it which is not making the liquid dispensing any less precise or accurate.
I have the same issue with Elos and Salifert...the Elos kit test about 1 dkh lower then the Salifert, but as someone said 1 dkh is not that big of a deal.
I don't want to hijack the thread, but what are people using for phosphate...anything reliable out there? I currently have used API, Salifert, Elos, Hanna checker, and a Milwaukee checker. The Hanna and Milwaukee seem to give a wide range of results so they are a little hard to trust. The API and Salifert always seem to give the same results <.01ppm, which is good if it were actually true. Just today I used the Milwaukee first and it came back with a reading of .25. I then had to run through all the other test to confirm. Just wondering what methods people are using...
Thanks for your time.
I don't want to hijack the thread, but what are people using for phosphate...anything reliable out there? I currently have used API, Salifert, Elos, Hanna checker, and a Milwaukee checker. The Hanna and Milwaukee seem to give a wide range of results so they are a little hard to trust. The API and Salifert always seem to give the same results <.01ppm, which is good if it were actually true. Just today I used the Milwaukee first and it came back with a reading of .25. I then had to run through all the other test to confirm. Just wondering what methods people are using...
Thanks for your time.
Okay Randy. It's just disconcerting to me is all. I keep wanting to push it out and have it all 'full of liquid'
Also your/the Porsche's turbo full of liquid?
