My latest Params, and why, oh why are some kits have such different readings?

Hello all, Here I sit and write my findings and my questions about keeping our little sections of the ocean, and/or reefs in captivity.

I tested all the params I have to test today, they were:

Ph 8.1- API (It was 8.3, 2 days ago, don'/t test it that much)
Alk- 9- API (lately it's been reaidng 9)
Phos- 0- API
NO3(nitrate)-0- API (the Phos and nitrate I don't test much, cause every time I do, the API reads a bright yellow= 0 )

Mg- 1350- Salifert
Ca+- 430- Salifert
Ca+- 320- API ??

I read and follow the directions very carefully- and have done eash many times.

I'm inclined to think the Salifert is more accurate for my Ca+, solely b/c I know how I've been daily dosing Ca+, sometimes Alk, and even adding some to my topoff water ATO.

Why would they be that far off each other- well, I know many of the reasons, but why are they? Should they be?

What I'd really like to know is:
- for instance the Sal. Ca+- it says if youy want more tests, to use 1/2 the test water, half the drops, and USE HALF A SPOON FULL of the powder?
How can you really estimate half a spoon full of the powder?
I know it says it's less accurate, but?

And,

Like for the Sal. Mg, can't you add about 80% of the last solution all at once and swirl for about 10secs, then go drop by drop?
The Sal. Ca+ says you can, why not the Sal. Mg?
And,
Can't you add two drops at the same time for the first 12-16drops,
then drop by drop?

And, are the tolerances of the bottle production so accurate, that 6 or 10 drops of one test, is the SAME volume/quantity as another test kit?

These are things I wonder as I try and keep my little scratch of a reef alive and well.
Luckily for me, (knocking on wood), things are going rather well.

Thanks for your logical, educated answers to my rambling questions.

 

Hey there all,

39 views, and no possible answers to my ?'s

Maybe it's obvious, redundant, or ?

 

Well like you said sometimes measuring the regents isn't exact, plus some test are just more accurate. API tends to be on the less accurate side of tests.