People with Hannah PO4 colorimeter please help.

[icliao]

How do you shake the bottle after adding the reagent powder.

The instruction indicates to shake gentlely but how gentle and shake for how long? Until all reagent disolved?

I found the result tend to be very high if I shake vigorously until all powder melt. I even yeild 0.02 - 0.03 reading with distill water if I shake hard. And if I don't shake it hard enough, the readings seemed to be reasonable but there is always some powder remains. Also the reading tend to change if I shake it after taking the reading.

It is all very inconsistent, please help.

 

[slojmn]

I invert the bottle back and forth fairly gently over the course of about 5 minutes. I swap out lids putting the other lid on before sticking it in the colormeter to read. The stuff leaked out before after gently shaking back and forth because the lid would get wet and for some reason was not water tight. I get good results this way. I think most all of the powder dissolves in this fashion pretty thoroughly.

 

[icliao]

<a href=showthread.php?s=&postid=8468686#post8468686 target=_blank>Originally posted</a> by slojmn
I invert the bottle back and forth fairly gently over the course of about 5 minutes. I swap out lids putting the other lid on before sticking it in the colormeter to read. The stuff leaked out before after gently shaking back and forth because the lid would get wet and for some reason was not water tight. I get good results this way. I think most all of the powder dissolves in this fashion pretty thoroughly.

I thought the instruction indicate to take reading at 3 min mark?
Do I need to dissolve all powder?
Do you get any reading from RO or distill water testing this way?
Do you change your bottle?

 

[slojmn]

You take the reading "for" 3 minutes, meaning that the timed reading is 3 minutes before the meter will give you the PO4 reading...it has a count down. You can shake and let sit for up to 9ish minutes after you zero the water sample...the hannah colormeter has an auto shut off after sitting idle for 10 minutes. You should get all of the powder to dissolve the best you can.

You can test RO/DI water as well...same way.

 

[clkwrk]

Shaking it increases turbidity which interfers with the reading . I gently swirl until all powder is dissolved.

The 3min count down is just to make sure that the sample has time to calm before a reading is taken .

 

[Serioussnaps]

i like your quote