Can anyone actually read the Salifert Phosphate test?

[jasonrusso]

I recently bought the Salifert P04 test kit because I had the Red Sea pro kit, and the color always looked the same but never really lined up to a specific value.

I was kind of disappointed that the 0 and 0.03 were pretty much identical. I THINK that it's 0, but the first 2 (actually 3) are so close that it's hard to tell. I have even done it outside so I am using sunlight.

 

[jeffp1]

I went to the Hannah Checker because of that reason. I couldn't tell the difference either.

 

[Randy Holmes-Farley Verified Community Expert]

I recently bought the Salifert P04 test kit because I had the Red Sea pro kit, and the color always looked the same but never really lined up to a specific value.

I was kind of disappointed that the 0 and 0.03 were pretty much identical. I THINK that it's 0, but the first 2 (actually 3) are so close that it's hard to tell. I have even done it outside so I am using sunlight.

I agree, that's generally the issue that determines the precision at the low end of most kits.

 

[jp_75]

get hanna checker... problem solved

 

[jasonrusso]

I agree, that's generally the issue that determines the precision at the low end of most kits.

Is there another kit that you recommend? Can I add 2x the solution and divide the result?

 

[jasonrusso]

get hanna checker... problem solved

Yes, but doesn't the Hanna still basically use a color metric internally and analyzes it by itself?

Wouldn't this still have the same issue as the other tests?

 

[themcfreak]

Yes, but doesn't the Hanna still basically use a color metric internally and analyzes it by itself?

Wouldn't this still have the same issue as the other tests?

There is a margin of error for Hanna, yes. And did you get all the powder in the cuvette? Does some miss and that affect results? However, at such a low end, as long as you get steady results, does it make a huge difference?

 

[jasonrusso]

There is a margin of error for Hanna, yes. And did you get all the powder in the cuvette? Does some miss and that affect results? However, at such a low end, as long as you get steady results, does it make a huge difference?

Agreed. My current issue is that I am dosing Vibrant because of a nasty GHA outbreak. I think that vibrant has strains of bacteria that consume P04 and N03, and also consume algae.

The algae is dying, but my SPS are not showing full PE. I think it is because the PO4 is getting stripped out. I can't tell if it is zero (requiring P04 dosing or crazy feeding) or 0.03 (no action taken).

 

[JVU]

Yes, but doesn't the Hanna still basically use a color metric internally and analyzes it by itself?

Wouldn't this still have the same issue as the other tests?

No, because the problem is your eye/brain ability to discern color differences and compare with a standard, whereas the spectrophotometer in the checker doesn’t have a problem with that.

 

[tiggs]

I've been having this issue with most test kits lately, so maybe my eyes are going on me. I've been slowly migrating over to Hanna Checkers because of this. The only one I won't touch is calcium, because it's apparently either wildly inaccurate or the margin of human error due to the tiny liquid amounts is too great.

 

[jasonrusso]

I've been having this issue with most test kits lately, so maybe my eyes are going on me. I've been slowly migrating over to Hanna Checkers because of this. The only one I won't touch is calcium, because it's apparently either wildly inaccurate or the margin of human error due to the tiny liquid amounts is too great.

I've been told that the alk checker is innacurate too. I don't have a problem with that one. I use the tritation tests

 

[themcfreak]

I've been told that the alk checker is innacurate too. I don't have a problem with that one. I use the tritation tests

I use the Hanna Alk checker. I think it is great. And I regularly do a Red Sea Alk test too, just to double check, and it is always good for me

 

[ZachR32]

You can double sample volume and reagents for the salifert test. I forget how much the results are changed but it should say in the little pamphlet with the kit

 

[Scrubber_steve]

I recently bought the Salifert P04 test kit because I had the Red Sea pro kit, and the color always looked the same but never really lined up to a specific value.

I was kind of disappointed that the 0 and 0.03 were pretty much identical. I THINK that it's 0, but the first 2 (actually 3) are so close that it's hard to tell. I have even done it outside so I am using sunlight.

I use the salifert po4 test kit.
Distinguishing zero from 0.03 is easy.
I found that using a second vial with tank water in it as a comparison to the test vial solution clearly diferenciates zero from 0.03. Or in other words, the test solution i thought was crystal clear actually had a blue tint when compared to the second vial.

 

[jasonrusso]

I use the salifert po4 test kit.
Distinguishing zero from 0.03 is easy.
I found that using a second vial with tank water in it as a comparison to the test vial solution clearly diferenciates zero from 0.03. Or in other words, the test solution i thought was crystal clear actually had a blue tint when compared to the second vial.

That's a good idea!

 

[rkpetersen]

The only one I won't touch is calcium, because it's apparently either wildly inaccurate or the margin of human error due to the tiny liquid amounts is too great.

I like the Hanna calcium checker very much, and have found it to be quite accurate when correlated with Triton/ATI results, but agree that it does require meticulous technique and true 0 TDS RODI water. Hanna recently introduced a dedicated pipette that dispenses exactly the right amount of fluid (o.1 ml) for this test, but I still prefer using a 1 ml syringe and find it's just as accurate for me.

 

[jasonrusso]

The Hannah checker has an accuracy of 0.04ppm. If that's the case, so do my eyes. That means if the sample is 0.04, it could read 0.00 or 0.08. That's the difference between algae and no algae, correct?

I can see 0.1, but it's close. I think I will try the 2 vials

 

[tiggs]

The Hannah checker has an accuracy of 0.04ppm. If that's the case, so do my eyes. That means if the sample is 0.04, it could read 0.00 or 0.08. That's the difference between algae and no algae, correct?

I can see 0.1, but it's close. I think I will try the 2 vials

This is true, although the Hanna ULR Phosphorous checker is much more accurate. The regular Phosphate checker isn't accurate enough for today's demands, IMO.

 

[kyleinpdx]

Personally, I think seachem phosphate is the best of PO4 tests out there. I've found it much easier to read than the rest.

 

[JVU]

The Hanna ultra low range phosphorus checker is much easier and more reliable to read than any of the colorimetric manual tests I’ve tried for the low range that most of our tanks are at. For me it’s a night and day difference; the difference between it being useful to check phosphate vs not. If I couldn’t use the Checker anymore I would probably just stop routinely checking phosphate.