Testing Methods

[Eel Freak]

What brand of titration test kit is generally regarded as most accurate around here? Salifert? I have used Salifert, API, SeaChem, and TropicMarin. They all seem to read different things....

[disc1]

I think acuracy comes down to the user and how well they understand the (often poorly written) instructions.

IMO precision is the more important quality. Choose the test that YOU are able to get the most consistent results from.

For example, let's imagine three kits checking calcium on the same sample of water five or ten times each to get a range of results:

test X 380 - 400

test Y 450 - 500

test Z 320 - 325

Just as an example.

Test Z is obviously giving low results, but look at the precision. Within 5ppm every time. Test Y may actually be closer to the real number, but you have a 50ppm spread. If we just ran the test once, how would we know which end of the spread we were on?


If the corals are happy on the day we ran those tests, then we have options. Use test Z and target 320, use test Y and target 475, or use test X and target 390. I think using the more precise test, will help us keep the coral happier, even though we may be off the real measurement by quite a bit. What it does, is allows us to keep our numbers more consistent, they will fluctuate less, and that stability is the key to a happy reef.

[Eel Freak]

Originally Posted by disc1

I think acuracy comes down to the user and how well they understand the (often poorly written) instructions.

IMO precision is the more important quality. Choose the test that YOU are able to get the most consistent results from.

For example, let's imagine three kits checking calcium on the same sample of water five or ten times each to get a range of results:

test X 380 - 400

test Y 450 - 500

test Z 320 - 325

Just as an example.

Test Z is obviously giving low results, but look at the precision. Within 5ppm every time. Test Y may actually be closer to the real number, but you have a 50ppm spread. If we just ran the test once, how would we know which end of the spread we were on?


If the corals are happy on the day we ran those tests, then we have options. Use test Z and target 320, use test Y and target 475, or use test X and target 390. I think using the more precise test, will help us keep the coral happier, even though we may be off the real measurement by quite a bit. What it does, is allows us to keep our numbers more consistent, they will fluctuate less, and that stability is the key to a happy reef.

Thank you. That makes wonderful sense. I've never thought of it that way...