Hanna PO4 Photometer Precision

[Aqua Pro Builder]

the manual said it doesn't need to be totally disolve

 

[alrha]

the manual said it doesn't need to be totally disolve

i know, but you want it to be mostly dissolved, no?
how long do you mix then before starting the timer?

 

[Alex]

if it doesn't dissolve all the way, then how are you getting an accurate reading or for that matter consistent ?

I do the readings the same way all the time that way at least its consistent.
-- get my water sample,pour the reagent,stir until dissolved, then timed reading.

I would think that if you don't wait for the reagent to dissolved, that's like not putting in enough reagent.

 

[alrha]

but alex, your timing then may not be consistent

 

[Alex]

timing for what ? dissolving the reagent ? already done it takes the reagent sec. to dissolve 10-15 with stirring.

 

[ecvernon]

i never really timed myself but it doesn not take more than a minute maybe not even more than 45 seconds to dissolve the reagent fully.



5) I then press the "Read Timed" button and swirl/shake the sample till the timer is down to 1:00.

alrha im not sure if this step you take would be correct because the manual says
-put reagent in tube
-replace cap then shake
-then put cuvet into instrument
-THEN PRESS THE READ TIMED BUTTON
it seems that the reagent is intended to sit for three mintes no matter what after it has been mixed

 

[alrha]

right, thats what i was wondering. so you first allow 1 minute for mixing then 3 minutes to sit? but then the reagent has been reacting for 4 minutes rather than 3.
isnt there also a button for an immediate test if you are mixing yourself?

 

[KathyC]

Albert..I do not include the time I shake the vial after adding the reagent as I can usually make the powder mix completely within 60 seconds tops. I then insert it into the unit (after wiping it down for fingerprints) and leave it alone while I run the 'timed' read test.
By the time the 3 minutes is up - the powder has always totally dissolved on it's own (if there was any small amount still present when I inserted it.)

Why not use the 'Read Direct' button if you have dissolved all of the powder by 'hand'?

I will try it with both methods and also by delaying putting it into the meter later tonight and see if it makes any difference.

Nice to be caught up on all of my water changes

 

[alrha]

ok, so i cleaned the glass well and first mixed it before setting it down and pressed read timed. the result on the distilled water..... 0.04!