Go Back   Aquarium Advice - Aquarium Forum Community > Saltwater and Reef > Saltwater Reef Aquaria
Click Here to Login

Join Aquarium Advice Today
Reply
 
Thread Tools Search this Thread Display Modes
Please support our sponsors and let them know you heard about them on AquariumAdvice.com
 
Old 01-22-2015, 11:47 PM   #71
AA Member
Community Moderator
 
Delapool's Avatar



POTM Champion
Tank of the Month Award
 
Join Date: Feb 2013
Location: Perth, Australia
Posts: 13,555
Quote:
Originally Posted by Mebbid View Post
Ahh, I gotcha. I thought you were saying that the 70 drops was going to give you a 14 dKh. I must've misread it.



Just for shiggles I measured the volume for drops and 70 drops gives a 10.6 dKh measurement. That's why I said "roughly" 0.01mL / drop. Not that it matters.



However, to get my point across this is straight from the red sea site:





And so we are on the same page; here's the definition of accuracy "The accuracy of a measurement is how close a result comes to the true value."



So assuming that you are measuring a reference solution with a known value of 4dKh you will get somewhere between 3.86 and 4.14 if you take the statement by red sea by its literal meaning.

I think that was what I was curious on as it seems to imply the accuracy isn't constant but improves (as a percentage) as you get higher values.

For example 1.14 (true value 1) is not as accurate as 10.14 (true value 10).

It seems odd?
__________________

__________________
Delapool is online now   Reply With Quote
Old 01-23-2015, 02:35 AM   #72
Aquarium Advice Addict
 
Caliban07's Avatar


 
Join Date: Aug 2013
Location: Manchester UK
Posts: 5,313
Quote:
Originally Posted by Delapool View Post
I think that was what I was curious on as it seems to imply the accuracy isn't constant but improves (as a percentage) as you get higher values.

For example 1.14 (true value 1) is not as accurate as 10.14 (true value 10).

It seems odd?

It doesn't matter. The accuracy is always 0.14 +- it is accurate to -+ 0.14 regardless of the true value.

That's the specification of the test kit, Would be interesting to check that though. Be good if it was.

Lol -+ 0.14 per drop...


Sent from my iPhone using Aquarium Advice
__________________

__________________
Caliban07 is offline   Reply With Quote
Old 01-23-2015, 02:41 AM   #73
Aquarium Advice Addict
 
Mebbid's Avatar



POTM Champion
 
Join Date: Mar 2013
Location: Michigan USA
Posts: 12,569
Quote:
Originally Posted by Caliban07 View Post
It doesn't matter. The accuracy is always 0.14 +- it is accurate to -+ 0.14 regardless of the true value.

That's the specification of the test kit, Would be interesting to check that though. Be good if it was.

Lol -+ 0.14 per drop...


Sent from my iPhone using Aquarium Advice
What Delapool is getting at is that at 1dkh the test kit could be off by as much as 14% while at 10dkh Its only 1.4%
__________________
"The simplest explanation for some phenomenon is more likely to be accurate than more complicated explanations." -Occam's razor
Mebbid is offline   Reply With Quote
Old 01-23-2015, 03:49 AM   #74
AA Member
Community Moderator
 
Delapool's Avatar



POTM Champion
Tank of the Month Award
 
Join Date: Feb 2013
Location: Perth, Australia
Posts: 13,555
Quote:
Originally Posted by Mebbid View Post
What Delapool is getting at is that at 1dkh the test kit could be off by as much as 14% while at 10dkh Its only 1.4%

Yes - that's it.

It's probably pretty irrelevant but I was interested as a lot of our work here depends on (assay) measurements and I've developed a morbid interest.
__________________
Delapool is online now   Reply With Quote
Old 01-23-2015, 08:11 AM   #75
Aquarium Advice Addict
 
Caliban07's Avatar


 
Join Date: Aug 2013
Location: Manchester UK
Posts: 5,313
Quote:
Originally Posted by Delapool View Post
Yes - that's it.

It's probably pretty irrelevant but I was interested as a lot of our work here depends on (assay) measurements and I've developed a morbid interest.

Yeh I get what you mean, I was speaking from a manufacturer perspective when I said it doesn't matter. As long as the reading is within their spec then they are in the clear.

As for the percentage accuracy. I suspect the 0.14dkh accuracy claims will only be valid within a certain range of dkh? Do marine setups typically see low levels of dkh? What would be considered a low dkh in a marine set up?


Sent from my iPhone using Aquarium Advice
__________________
Caliban07 is offline   Reply With Quote
Old 01-23-2015, 08:51 AM   #76
Aquarium Advice Addict
 
Mebbid's Avatar



POTM Champion
 
Join Date: Mar 2013
Location: Michigan USA
Posts: 12,569
Quote:
Originally Posted by Caliban07 View Post
Yeh I get what you mean, I was speaking from a manufacturer perspective when I said it doesn't matter. As long as the reading is within their spec then they are in the clear.

As for the percentage accuracy. I suspect the 0.14dkh accuracy claims will only be valid within a certain range of dkh? Do marine setups typically see low levels of dkh? What would be considered a low dkh in a marine set up?


Sent from my iPhone using Aquarium Advice
That information was never supplied so I can't say whether it is or not.

Low dkh would be around 7 and its not really typical to see as the live rock works to buffer and coral will stop absorbing it when it gets low.
__________________
"The simplest explanation for some phenomenon is more likely to be accurate than more complicated explanations." -Occam's razor
Mebbid is offline   Reply With Quote
Old 01-23-2015, 09:46 AM   #77
AA Member
Community Moderator
 
Delapool's Avatar



POTM Champion
Tank of the Month Award
 
Join Date: Feb 2013
Location: Perth, Australia
Posts: 13,555
I did hunt around tech info and FAQ but no luck. Was just curious.
__________________
Delapool is online now   Reply With Quote
Old 01-23-2015, 04:43 PM   #78
Aquarium Advice Addict
 
Caliban07's Avatar


 
Join Date: Aug 2013
Location: Manchester UK
Posts: 5,313
Did a bit more hunting round today while I was at work. Emailed tech support at red sea.

It must have sounded like I was questioning the accuracy of the kit lol

Here is the response

Thank you for contacting Red Sea.
The accuracy variation quoted of 0.05 meq/l is as you correctly suggest 0.14 dKH, this error factor is added if the dKH is 1.0 or 10 as you suggest, the test kit is designed for use on Sea water aquariums with an optimum dKH range between 8 and 13, the test kit will give you a suitability accurate result in the optimum range.

Whilst the test is easy to perform there are very many factors behind the test that can cause the test to vary, the pH of your aquarium being one of them, this variation would add to the error at a very low range but as stated in the normal range we are confident the test kit works with a high accuracy.

Regards

Kevin Davies
Technical Support Manager
Red Sea Group

So it would seem that there is a range in which the test is more accurate as they are not expecting to typically see a dkh of less than the lower value of their "optimum range"

Hope this helps?


Sent from my iPhone using Aquarium Advice
__________________
Caliban07 is offline   Reply With Quote
Old 01-23-2015, 09:59 PM   #79
AA Member
Community Moderator
 
Delapool's Avatar



POTM Champion
Tank of the Month Award
 
Join Date: Feb 2013
Location: Perth, Australia
Posts: 13,555
Quote:
Originally Posted by Caliban07 View Post
Did a bit more hunting round today while I was at work. Emailed tech support at red sea.

It must have sounded like I was questioning the accuracy of the kit lol

Here is the response

Thank you for contacting Red Sea.
The accuracy variation quoted of 0.05 meq/l is as you correctly suggest 0.14 dKH, this error factor is added if the dKH is 1.0 or 10 as you suggest, the test kit is designed for use on Sea water aquariums with an optimum dKH range between 8 and 13, the test kit will give you a suitability accurate result in the optimum range.

Whilst the test is easy to perform there are very many factors behind the test that can cause the test to vary, the pH of your aquarium being one of them, this variation would add to the error at a very low range but as stated in the normal range we are confident the test kit works with a high accuracy.

Regards

Kevin Davies
Technical Support Manager
Red Sea Group

So it would seem that there is a range in which the test is more accurate as they are not expecting to typically see a dkh of less than the lower value of their "optimum range"

Hope this helps?


Sent from my iPhone using Aquarium Advice

That's brilliant! Thanks for the post back. Will have to check them out when the API one runs out (some time away though).

Our assays are a little like that. There is the lower assay detection limit (say 0.01% fe). But really we don't get a stable assay reading until something like say 1% fe. The machine isn't really calibrated down that low as only interested in above say 40% fe.
__________________
Delapool is online now   Reply With Quote
Old 01-24-2015, 05:25 AM   #80
Aquarium Advice Addict
 
Caliban07's Avatar


 
Join Date: Aug 2013
Location: Manchester UK
Posts: 5,313
Quote:
Originally Posted by Delapool View Post
That's brilliant! Thanks for the post back. Will have to check them out when the API one runs out (some time away though).

Our assays are a little like that. There is the lower assay detection limit (say 0.01% fe). But really we don't get a stable assay reading until something like say 1% fe. The machine isn't really calibrated down that low as only interested in above say 40% fe.

Yeah I think it depends what you're trying to test. Sometimes readings at a higher level are more unstable and so the tolerance for accuracy becomes a lot wider. Pressure inside an inflated chamber may be one of them where the tolerance is a lot wider at a higher pressure.


Sent from my iPhone using Aquarium Advice
__________________

__________________
Caliban07 is offline   Reply With Quote
Reply

Tags
co2

Please support our sponsors and let them know you heard about them on AquariumAdvice.com

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
CO2: KH/PH Chart Delapool Freshwater & Brackish - General Discussion 4 12-10-2013 10:56 PM
KH-PH Co2 chart, plus Bubbles per minute sudz Freshwater & Brackish - Planted Tanks 9 11-28-2012 04:47 PM
CO2 chart (KH to pH relationship) Angry the Clown Freshwater & Brackish - Planted Tanks 3 01-20-2007 11:22 AM
CO2 Yeast - Chart CaptnIgnit Freshwater & Brackish - Planted Tanks 7 08-16-2006 03:51 PM
does this chart look right too you? e-cat Saltwater Reef Aquaria 2 11-28-2003 04:41 PM







» Photo Contest Winners








Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -4. The time now is 09:43 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.