PO4 test kits - Hanna VS Salifert

[Myka]

Originally Posted by GoFish

Well may need to work in my precision testing skills just a touch. I learned from having the calcium checker that these things can be super finicky. I was never able to get anywhere near consistent back to back readings with the calcium checker so ended up selling it and sticking with Salifert.

The calcium checker is horrible. It's not your fault. That checker is NOT user friendly, and few people can report consistent, repeatable results.

Originally Posted by GoFish

Potatohead & Mindy: May put a microfibre towel with the checkers from now on, good idea.
Mindy: Not sure about drying the vial inside with paper towel before testing, i'd wonder about getting fibres left behind in the vial? Good call on leaving the vial out for the 3 minutes countdown to give it one more shake, will try this. Do you think rinsing it with hot water makes any difference? I just use cold usually

The hot water rinse and drying at the end is to remove any blue residue inside the vial since the blue color (which may or may not actually be visible to you) sticks to the vial, and over time will leave a "stain" that takes some serious scrubbing to remove, and because of the shape of the vial scrubbing is difficult. The tank water rinse at the beginning is to remove any fibers from the drying of the vial before storage. Since tap water could easily throw off the readings I use tank water. I doubt there are any fibers introduced when I clean the top of the vial curing the process as I'm really just putting it gently in the opening and the paper towel wicks any drops out, there isn't much movement of the paper towel.

[Delphinus]

Re. the Calcium checker - what, people have trouble retrieving only a single molecule of tank water? Who could have foreseen that!!!!

[gregzz4]

Meant to reply last week but got busy and forgot.

Mindy, have you performed back to back tests to see if your procedure gives you a different reading than the instructions' procedure would?
One test your way and one test the Hanna way?

I ask because you're supposed to;
Swirl or whatever for 2 minutes, then insert the cuvette and hold the button to start the 3 minute countdown.
I double-checked; their online video shows it this way.

What I gather is the full countdown allows any un-dissolved powder to settle before it takes the reading.

I use the regular model HI713 and find it's always been reliable by doing the above, even with back to back tests - ya know, for those times when it reads 'what the hell? It can't be that high!'

[Ryanerickson]

I tried mindys method it gets me way lower results, 4-6 ppb so almost none existent I'm also questioning if this method is correct as its not what the instruction say to do,
I also watched a video they did not use this method either.
How did you get this method for testing mindy?

[Myka]

Originally Posted by gregzz4

Mindy, have you performed back to back tests to see if your procedure gives you a different reading than the instructions' procedure would?
One test your way and one test the Hanna way?

What I gather is the full countdown allows any un-dissolved powder to settle before it takes the reading.

I've never watched their videos - actually I didn't know they made any. I'm not sure what I'm doing differently from "the Hanna way"? Could you explain? The method I use is one that is very common with the "purists" (lol) on Reef Central and Reef2Reef, and supposedly the proper way to do it.

I never get undissolved powder, so I'm not sure what's up with that. However, the countdown is for color development.

Originally Posted by Ryanerickson

I tried mindys method it gets me way lower results, 4-6 ppb so almost none existent I'm also questioning if this method is correct as its not what the instruction say to do,
I also watched a video they did not use this method either.
How did you get this method for testing mindy?

See above. What am I doing different?

[Ryanerickson]

Well in the instruction from what I understand you poor the powder into vial right after c2 is displayed when it's dissolved you add to unit and hold botton tell 3:00 countdown starts.

[Ryanerickson]

I prefer your method as its easier but what's right