Salifert vs hannah for phosphate...which one is lying to me?

Miami Reef

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I tested my water with Hannah PPB and salifert phosphates and I got 2 different results.

the Hannah came out to 0.058 and the salifert came out as 0 (water was crystal clear). I tested phosphates twice with the salifert and I got crystal clear water. I’m confident that I tested correctly with the salifert.

With the Hannah, I filled to the 10ml line. Wiped the container and inserted it. I made sure I fiddled with the bag to get all the reagent in the bottom and made a funnel to get all the powder out. I gently turned the bottle upside down and right side up to incorporate the solution without causing bubbles.

Tank was recently cycled and I had a bag with phosguard inside a high flow area. Before I added the phosguard Hannah told me that it was 0.089ppm. I purchased the salifert test kit because I wanted a less complicated way to test. I didn’t like to Hannah’s powder tended to come out when the paper sealant ripped. I didn’t like the auto shut off timer.

I don’t have any algae in my tank. I had my lights turned on for a few hours a day and I only developed a very very light haze on the glass...that was because I left out of town for a week...

Nitrates are 50ppm (down from 100ppm) using salifert.

how did I get it down? Water change and vodka. I tested after coming back (no water change nor vodka for a week) and it appears the rocks stopped leeching organics.
 

nereefpat

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Trust the Hanna. It is more useful in that (ultra) low range. That's what it is for.
 

Randy Holmes-Farley

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The Salifert is just a shade of color. I would trust the Hanna provided you cleaned that vial well;).

The Hanna is also just a shade of color. :)
 

Randy Holmes-Farley

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Would you agree that a spectrophotometer/colorimeter is better at distinguishing between shades of color, especially when the shades are very light?
Probably yes.

But a scratch might also give a false high reading.
 

ultraArcite

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I tested my water with Hannah PPB and salifert phosphates and I got 2 different results.
I highly recommend sending your water out for an ICP test or something similar. I had two different values for pH. I thought 1 value was correct but I sent my water out and the one I thought was wrong was correct. It's nice to verify your results once a quarter or so.
 

Daniel92481

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Definitely shake the Hanna vigorously for 2 minutes after you add the powder. After 2 min, wipe the vial clean and put it in the Hanna checker, press and hold the button to wait the three minutes.
 

puffdragon

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I go with the Hanna for this reason, 99.9 % of the people cannot see the color difference and if you are a guy, the percentage is closer to 100%....but when we get this close, you are looking at virtually the same number.
 

Tcook

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I brought my water and Hana tester into my lfs to test against his Salifert. I got 0.8 on the Hana. He got 0.0 on the Salifert
 

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