Neptune trident

ksfulk

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One interesting question is the quoted accuracy of an individual test. I would be interested (and Im sure Neptune will provide this data) to see on what this claim is based. Usually when stating a test is accurate to xxx degree, there is a gold standard test to which the other test is compared. Im not sure what that is in the case of Trident. If the Trident is accurate to within .05 dKH, I guess that means that if one takes 3 samples of the same water, all three measurements will come within .05 dKH of each other. However, is that the same as saying that the dKH is within .05 of the 'actual' dKH of the sampled water?

You are confusing accuracy and precision:

Accuracy refers to the closeness of a measured value to a standard or known value. For example, if in lab you obtain a weight measurement of 3.2 kg for a given substance, but the actual or known weight is 10 kg, then your measurement is not accurate. In this case, your measurement is not close to the known value.

Precision refers to the closeness of two or more measurements to each other. Using the example above, if you weigh a given substance five times, and get 3.2 kg each time, then your measurement is very precise. Precision is independent of accuracy. You can be very precise but inaccurate, as described above. You can also be accurate but imprecise.

For example, if on average, your measurements for a given substance are close to the known value, but the measurements are far from each other, then you have accuracy without precision.

A good analogy for understanding accuracy and precision is to imagine a basketball player shooting baskets. If the player shoots with accuracy, his aim will always take the ball close to or into the basket. If the player shoots with precision, his aim will always take the ball to the same location which may or may not be close to the basket. A good player will be both accurate and precise by shooting the ball the same way each time and each time making it in the basket.​
 

MnFish1

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You are confusing accuracy and precision:

Accuracy refers to the closeness of a measured value to a standard or known value. For example, if in lab you obtain a weight measurement of 3.2 kg for a given substance, but the actual or known weight is 10 kg, then your measurement is not accurate. In this case, your measurement is not close to the known value.

Precision refers to the closeness of two or more measurements to each other. Using the example above, if you weigh a given substance five times, and get 3.2 kg each time, then your measurement is very precise. Precision is independent of accuracy. You can be very precise but inaccurate, as described above. You can also be accurate but imprecise.

For example, if on average, your measurements for a given substance are close to the known value, but the measurements are far from each other, then you have accuracy without precision.

A good analogy for understanding accuracy and precision is to imagine a basketball player shooting baskets. If the player shoots with accuracy, his aim will always take the ball close to or into the basket. If the player shoots with precision, his aim will always take the ball to the same location which may or may not be close to the basket. A good player will be both accurate and precise by shooting the ball the same way each time and each time making it in the basket.​
Hi - No I'm not confusing accuracy and precision. I was curious whether the statements made by Neptune concerning the .05 dKH were .05 dKH +- from a standard (and I was wondering what that standard was i.e. how it was measured) or whether they were saying measurements on the same sample would be within .05 dKH of one another. But I agree with you that I wasn't as precise as I could have been in expressing the question:). (Actually, I was wondering if Neptune was talking about precision as compared to 'accuracy')
 

ksfulk

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Hi - No I'm not confusing accuracy and precision. I was curious whether the statements made by Neptune concerning the .05 dKH were .05 dKH +- from a standard (and I was wondering what that standard was i.e. how it was measured) or whether they were saying measurements on the same sample would be within .05 dKH of one another. But I agree with you that I wasn't as precise as I could have been in expressing the question:). (Actually, I was wondering if Neptune was talking about precision as compared to 'accuracy')

Since we are dealing with assumptions, I guess we will have to wait for some official response. That said, I'm sure its been tested for both accuracy AND precision. Known dKH standards are available - I believe RHF has a recipe for some in the chemistry forum - and even Jim's prototype claimed pretty narrow bands of accuracy (+/- 0.1 dKH I believe) even with the added conversion factor for the pH probe. It would be just silly to not to.

I'm interested to see the data as well. :D
 

MnFish1

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Since we are dealing with assumptions, I guess we will have to wait for some official response. That said, I'm sure its been tested for both accuracy AND precision. Known dKH standards are available - I believe RHF has a recipe for some in the chemistry forum - and even Jim's prototype claimed pretty narrow bands of accuracy (+/- 0.1 dKH I believe) even with the added conversion factor for the pH probe. It would be just silly to not to.

I'm interested to see the data as well. :D

Right:). Thanks why I asked. Since Terrence is reading these forums, I assumed we would get an answer.
 

Daniel@R2R

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Right:). Thanks why I asked. Since Terrence is reading these forums, I assumed we would get an answer.
He may answer here, but you might get a quicker response if you post that question in his FAQ thread. My understanding is that he's asking people to take their questions for him to that thread.
 

drsalomon

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The trident is large. What is the maximal length of tubing that will go to my tank to withdraw sample water? I have limited space in my sump
 

VelocityTech

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PS - To the person that stated their 'Mg dropped 500 in 5 days'. was it a testing error - or why do you think your Mg dropped so much. Unless it was a nano tank, I would be surprised that any normal physiology would cause such a drop.

I have seen Magnesium drop 400-500 in one day. It's very possible to have it drop in 5 days.

Here's my case:
My MG dropped from 1280 to 850. It was not a MG Testing error, as I double tested and got the same results.
My mag was at 1280 ( I prefer it to be 1400-1500 ).
The only extra variable was doing a water change. I'm assuming the (Ca) got driven up, causing the MAG to fall.
Me personally; it happened after Testing and then dosing With a water change: 5 days.

I have found reefers that have had there Magnesium drop as much, in far less time.
As Calcium, and Magnesium change the understanding of coral Polyp physiology. We want data. And.

With the supporting data of Testing 2x daily of both, We can now we can dose MAG daily, More safely.

Surprised?
 
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Daniel@R2R

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MnFish1

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I have seen Magnesium drop 400-500 in one day. It's very possible to have it drop in 5 days.

Here's my case:
My MG dropped from 1280 to 850. It was not a MG Testing error, as I double tested and got the same results.
My mag was at 1280 ( I prefer it to be 1400-1500 ).
The only extra variable was doing a water change. I'm assuming the (Ca) got driven up, causing the MAG to fall.
Me personally; it happened after Testing and then dosing With a water change: 5 days.

I have found reefers that have had there Magnesium drop as much, in far less time.
As Calcium, and Magnesium change the understanding of coral Polyp physiology. We want data. And.

With the supporting data of Testing 2x daily of both, We can now we can dose MAG daily, More safely.

Surprised?

I don't know what 'surprised?' means. Surprised that you had a problem with your tank? I guess anything is possible.

I still don't see/understand your point . Mg shouldn't drop 'on its own' in a short period of time. (unless there is another significant imbalance in Ca/Alk which would be visible in testing). From a chemistry standpoint I don't see a clear reason that Mg should drop by 30+percent in a day from a water change unless the salt is poorly mixed or there is some other issue in your tank.

I assume that thousands / millions of aquarium keepers around the world decide to test Mg less frequently because they have found that more frequent testing is not needed (i.e. it doesn't vary that much from day to day) and there is no need to dose it differently.
 

alanjeffery

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^^^^^
"The only extra variable was doing a water change. I'm assuming the (Ca) got driven up, causing the MAG to fall"

Or was the water change water low in Mg?
You assumed the Ca got driven up, did you not test to confirm?
 

Sleepydoc

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I have seen Magnesium drop 400-500 in one day. It's very possible to have it drop in 5 days.

Here's my case:
My MG dropped from 1280 to 850. It was not a MG Testing error, as I double tested and got the same results.
My mag was at 1280 ( I prefer it to be 1400-1500 ).
The only extra variable was doing a water change. I'm assuming the (Ca) got driven up, causing the MAG to fall.
Me personally; it happened after Testing and then dosing With a water change: 5 days.

I have found reefers that have had there Magnesium drop as much, in far less time.
As Calcium, and Magnesium change the understanding of coral Polyp physiology. We want data. And.

With the supporting data of Testing 2x daily of both, We can now we can dose MAG daily, More safely.

Surprised?

What kind of test kit were you using? Mg is not consumed in any significant amount by the tank inhabitants, so that large of a drop is either testing error, or from the water change. Most salt mixes have some 'reasonable' amount of Mg in them, so it would have to have been a large water change with improperly mixed water to have that large of an effect.
 

markstubb

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I bought an alkatronic because I can’t imagine this thing will hit the market any time soon. I love the idea of it, but if it ends up like the COR, it gonna be a while...

I’ll gladly eat my hat if it shows up on schedule, but with Neptune’s history of tight lips, you’ll never know until the day it happens, which makes planning for one impossible.
 

MartinWaite

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I bought an alkatronic because I can’t imagine this thing will hit the market any time soon. I love the idea of it, but if it ends up like the COR, it gonna be a while...

I’ll gladly eat my hat if it shows up on schedule, but with Neptune’s history of tight lips, you’ll never know until the day it happens, which makes planning for one impossible.


I don't have Apex so for me to buy Trident I will have to purchase the Apex controller as well so it would work you very expensive so I'm going for the Alkatronic as well and from the feedback it's receiving a lot of good reviews. If it's as good as their Focuslight which I have it's a great piece of kit.
 

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