Let's talk about the hanna meters....

[ronnie]

Everyone edits their posts now..... ;D

 

[Troylee]

I'm really puZzeld...:squigglemouth:
Maybe there is a additive I am adding to my tank to get a false zero reading everytime...I know my po4 is low from vodka dosing but it can't be zero I see little patches of algae here and there and I dose on the very low side only .2ml of vodka on a 220gal tank.... Baffled like my sump....

 

[Oiseau Reefer]

OK, standards have gone out. Standards sent to ronnie, troylee, jcom, and oiseau reefer. I was only able to send about 45 mL of each standard. I realize that this isn't too much in that only 4 tests can be run, but greater volumes were going to get spendy to ship.

Hey thanks looks like Troylee's got to him still waiting for mine will this stuff break down over time and not be as accurate or does it stay constant

 

[Oiseau Reefer]

Looks like it just can't read I. The slightly lower than the tenths of a ppm we'll see I got the alk meter and let's just say no dice the professor at byu aka morman dating services is testing it out!! But he says there isn't anyway he can see it working with saltwater

 

[sowellj]

Glad to see these starting to come in. The standards should be stable indefinately. The standards would represent sort of the best case scenario ... easily accessible phosphate in MilliQ water (lab grade RO/DI). I will be curious to see how well their meter to meter reproducibility is. My guess is that potential problems with these lie in the use of ascorbic acid as a reagent. If I would have been thinking correctly, I should have mailed you guys some things to spike into the standards to see if they affected the results.

 

[sowellj]

Troylee - One thing that might be interesting to try: Get the 1ppm standard and do a 1:1 dilution with your tank water, i.e., 5 mL standard, 5 mL tank water. In theory, the results should come back as roughly 0.5 ppm. If they do not, then that suggests that there may be something in our tanks that interferes with the chemistry of the test.

 

[Troylee]

Great idea!!!! I will try that tomorrow... To lazy to do it tonight....lol

 

[Oiseau Reefer]

That sounds like a good Idea I'll do the same with my tank water when I get mine as well !

 

[darknessheir]

im so lost

 

[subielover]

So, according to the standards that Troylee was sent, it looks like it reads approximately 10% low.

 

[ronnie]

At higher concentrations, that appears to be the case. I'm curious what a .05 or .08 standard would read as?

Could we combine the .1 and .01 at some combo to get a different reading? What would those measurements be?

 

[HighlandReef]

thanks for going thru all this testing for us guys, i know life gets busy and its nice to see the results troylee got, had me wondering for a while and the 10% i can live with considering the cost of the thing
fixed typo

 

[ronnie]

Hoping to get my test solutions in the mail today. If I do, I'll post up some numbers later tonight.

 

[sowellj]

So for those interested in learning a bit about how these work ...
http://en.wikipedia.org/wiki/Beer%E2%80%93Lambert_law
I am guessing, they (hanna) initially form an inorganic phosphoric acid (phosphate), then reduce that product with vitamin C to form the 'blue color'. Light is then passed through this and the amount of light absorbed is proportional to the concentration of phosphate. Now, the dynamic range for Beer's law is limited. My guess is that things start to fall apart a bit as you get down to the lower end of the range.

 

[Troylee]

well my 1.0 solution read .90... so i will take 50 percent tank water and 50 percent 1.0 solution and see if i get a .45 reading since my tank measures all zeros.... "will try when i get home from work"....

 

[jcom]

Got my samples from Sowellj today! Thank you very much. Will post my results shortly.

 

[Oiseau Reefer]

I received min as well here are the results first is the 1.0ppm .05 off

 

[Oiseau Reefer]

Next was the .1 it was .04 off and of course the .01 came up 00000 across the board I'd like to try is against a .05 sample to test that!

 

[subielover]

I am happy we are getting some standards to test for p04, but I am much more interested in how accurate/inaccurate the alk checkers are.

 

[sowellj]

Let me read up a bit on how the alk meters work and I will see if I can do the same (make some standards) for those.