What brand of phosphate test kit are you using?

[H20Sidhe]

I use Salifert, and I am getting suspicious that it is not accurate with my tank water. Not simply due to the shades of blue being difficult to differentiate (which is true) and not simply because it isn't very sensitive in the low ranges (which is also true). I suspect that something is interfering with my results.

I was looking at some test kits today, and they vary widely in price. Before I invest a gazillion dollars, I'd like to know what you are using, and if you are satisfied. I would also like to know (any inorganic chemists out there?) the chemical reaction and/or reagents used in the kits so maybe I can find one using a different method than Salifert uses.

TIA

 

[tylorarm]

I was using Salifert but it basically doesn't tell you anything because if you have any reading at all you're way way too high. I just bought a Milwakee colorimeter and hope it helps me in the lower range readings. Particularly if my rowa filled reactor media is used up or not, I'd like to have confidence in my reading of input vs output. I believe the Rowa/Merck test is not accurate enough at lower levels so I'm hoping this works out (read about Rowa test for P not P04 in chemistry forum).

 

[MrMikeB]

I use Salifert as well, and have the same problem regarding the readings being rather useless save if there is a detectable level vs nothing. The color scheme is near impossible to distinguish the shades between readings. I have also used SeaChem for comparison with similar results so at least I have consistently (good/bad) test results.

 

[Sparkss]

we use a Hanna colorimeter

 

[CaptiveReefSystems]

Merck and it does go down to below 0.03 mg/l P or 0.092 mg/l PO4. I will have it at the meeting.

 

[fishsoldseprtly]

I am using Salifert also and I have the same probs with the test kit.

 

[tfp]

<a href=showthread.php?s=&postid=9019430#post9019430 target=_blank>Originally posted</a> by CaptiveReefSystems
Merck and it does go down to below 0.03 mg/l P or 0.092 mg/l PO4. I will have it at the meeting.

sweet! thats what i'm talkin' about bruce!
lookin' forward to having a few water samples tested tonight

 

[duec22]

Inorganic Chemist:wavehand:
However, I've never used one of those test kits...I just let my tank tell me how my phosphates are doing (ie. how much algea growth I've got) I'm sure since I run rowaphos all the test kits would be ND...
Since I've never used one of the test kits, I've got no idea on how they work. Is it a titration? Another thing to keep in mind is that as far as I know the test kits only test for orgainc phosphate...to get a total phosphate sample you have to digest it with acid first.
In the lab here we do a persulfate/sulfuric digestion, followed by treatment and anaylisis on a spectometer. We've got a method detection limit of about 0.04 mg/L. Wich is actually higher than what the test kits say they read to. However, I'm sure our 0.04 mg/L results are real and true, I'm not sure I would make the same claim with the kits.

If you give me a little info on the test kit (how it works), I'll take a look at a standards methods book and see if I can't find out how the kit is doing it's testing.

 

[CaliforniaDreamer]

Is your test reporting .04mg/l of PO4 or Phosphorus?

<a href=showthread.php?s=&postid=9022129#post9022129 target=_blank>Originally posted</a> by duec22
Inorganic Chemist:wavehand:
However, I've never used one of those test kits...I just let my tank tell me how my phosphates are doing (ie. how much algea growth I've got) I'm sure since I run rowaphos all the test kits would be ND...
Since I've never used one of the test kits, I've got no idea on how they work. Is it a titration? Another thing to keep in mind is that as far as I know the test kits only test for orgainc phosphate...to get a total phosphate sample you have to digest it with acid first.
In the lab here we do a persulfate/sulfuric digestion, followed by treatment and anaylisis on a spectometer. We've got a method detection limit of about 0.04 mg/L. Wich is actually higher than what the test kits say they read to. However, I'm sure our 0.04 mg/L results are real and true, I'm not sure I would make the same claim with the kits.

If you give me a little info on the test kit (how it works), I'll take a look at a standards methods book and see if I can't find out how the kit is doing it's testing.

 

[Paliya]

I use the salifert phosphate and always do the 'higher sensitivity test' now (double water+reagents, half the scale). It seems to produce better results.

-Pat

 

[funman1]

I use Salifert as well

 

[Marc Daniels]

Hanna colorimeter.

 

[duec22]

as P....You know not very many people know to ask that... esspecially our clients..
We get calls all the time asking "What does it mean Nitrate as N, or phosphate as P."

 

[xia]

How does a hanna colorimeter work? And what's the cost?