High phosphate???

[MightyMO]

I have a Hanna ulr phosphate colorimeter. Have gotten nothing but maxed out readings out of my tank... it says to dilute sample so I did. I used 50% di water and 50% sample. My reading is .39... what are my phosphates if I diluted the sample and got that reading???

 

[MightyMO]

The meter reads in ppm...

 

[MightyMO]

Bump

 

[Larry L]

If you dilute the sample by half, then you have to double the reading. So if the reading is .39 ppm then the actual phosphates are 0.78 ppm.

 

[MightyMO]

If you dilute the sample by half, then you have to double the reading. So if the reading is .39 ppm then the actual phosphates are 0.78 ppm.

So I did that, and that is below the max reading I keep getting out of the meter.... Why isn't the meter just telling me 0.78 ppm to begin with in a full sample???

 

[Larry L]

So I did that, and that is below the max reading I keep getting out of the meter.... Why isn't the meter just telling me 0.78 ppm to begin with in a full sample???

You're probably right near the high end of the checker range. The manufacturer accuracy says ±0.02 ppm ±5% of reading so a reading of 0.9 ppm with an undiluted sample could really be anywhere from 0.835 ppm to 0.965 ppm, plus whatever user error there might be with getting the reagent into the vial or getting the test timings right.

 

[MightyMO]

Ok, I really do appreciate your help. Just did a 50% water change, not sure why my number isn't lower...

 

[MightyMO]

Gonna start running some chemipure blue...

 

[Dan_P]

Ok, I really do appreciate your help. Just did a 50% water change, not sure why my number isn't lower...

PO4 adsorbs to aragonite. When you perform a water change, PO4 desorbs from the aragonite to bring the level back up.

 

[Reef.]

Gonna start running some chemipure blue...

Just to let you know, your tank build banner doesn’t link to your build, it links to the member tanks thread page.