Dosing Waterglass (silicates)

[ToadallyNC]

While dosing (waterglass), silicate, will the Hanna ULR Phosphate test give you higher than normal accurate readings?

 

[SlugSnorter]

While dosing (waterglass), silicate, will the Hanna ULR Phosphate test give you higher than normal accurate readings?

I don't think so

 

[ToadallyNC]

I don't think so

Reason I ask, there’s been talk on some of the Dinoflagellates forums that it does throw off the reading. They say it reads higher.

 

[ToadallyNC]

I don't think so

I also get a lower reading using the Red Sea Pro tests

 

[Mike konesky]

Never saw po4 testing issues when I was dosing silicate. Red sea pro always reads low imo. I'll get something like .15 Hanna .04 red sea.

 

[Randy Holmes-Farley]

@taricha @Rick Mathew

 

[Randy Holmes-Farley]

High Silica interference with PO4 measurement

Tip to @Jason mack who brought it up earlier in a dino thread. I was skeptical, but it seems to be true, and in some cases, it might change how we choose to dose and test etc. This is a combo of data from me and @Rick Mathew Saltwater spiked with different levels of Silica was measured for...

www.reef2reef.com

 

[Randy Holmes-Farley]

FWIW, silicate at more than 10 ppm (shouldn’t be dosing that high) will interfere with the Hach phosphate test, but it only reads down to 0.02 ppm so a device trying to read even lower may suffer silicate interference at lower silicate levels.

 

[taricha]

Right, it's gotta be a lot of silica.

This is a combo of data from me and @Rick Mathew

Saltwater spiked with different levels of Silica was measured for PO4 with the Hanna ULR P meter.
What is plotted is the difference in the PO4 measured value from its original (zero SiO2) value.
That Rick's (red) and my (blue) data are so closely in agreement given different Si sources etc makes the effect look likely to be real.

Is this a big effect? Not really. Hanna's Low Range Si checker maxes out at 2.00ppm SiO2. I know of no reason why anyone would want more than 2ppm SiO2. There is no evidence of significant interference at or below that range. But it looks like the interference starts around 2ppm SiO2 and becomes significant compared to the uncertainty in the PO4 test by 4ppm SiO2

So unless you have more than enough SiO2 to max out the hanna Si meter, you won't get detectable false high on the ULR P checker.

 

[ToadallyNC]

Thanks for all the reply’s.

 

[ToadallyNC]

How accurate is the Hanna high range silicate meters? Anyone here use them?

 

[Mike konesky]

Seems pretty accurate. Reagents are a bit pricey. Claimed accuracy of +-.03 or 5%. If you are using this meter to compare icp tests I believe Taricha knows the magical conversion.

 

[taricha]

How accurate is the Hanna high range silicate meters? Anyone here use them?

Why would you want the high range? The low range Si checker works great, is more relevant to hobby amounts, and you can just dilute the sample if your silica is out-of-range high.

 

[ToadallyNC]

Why would you want the high range? The low range Si checker works great, is more relevant to hobby amounts, and you can just dilute the sample if your silica is out-of-range high.

Hanna makes a low range?

 

[taricha]

Hanna makes a low range?

yep. that's what I and some others have used
https://www.hannainst.com/hi705-silica-lr.html

 

[ToadallyNC]

yep. that's what I and some others have used
https://www.hannainst.com/hi705-silica-lr.html

Thanks!

 

[ToadallyNC]

yep. that's what I and some others have used
https://www.hannainst.com/hi705-silica-lr.html

Does the meter come with a few reagents?

 

[taricha]

Does the meter come with a few reagents?

yeah, not many if I remember, maybe 6 or 10. Reagent refills are 25pack.