I don‘t know but I’ve read about and also experienced it. When I was dosing 1,0 ml daily, my test results were off the charts. I don’t remember the number but it was really high.
Between 1 and 2 ml. Last time was 2,0 ml.
I dose silica too (on and off). I’d definitely like to learn how dosing would affect my phosphate results.
Not yet. My last phosphate test came out as 0.03ppm though. That was before any silica dosing, although I do have a minor amount of diatoms.
Zero difference. (undetectable)
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.
Thank you very much.
I’ve heard this before…. When dosing high amounts of silicates (to beat dinos) the Hanna checker reads high results and it’s recommended to use a different kit for phosphate.
