Phosphate conversion question.....

[SPotter]

Randy, I am using the Martini Low Range Phosphate meter Milwaukee - Mi412 Phosphate (Low Range) Photometer and it says the range of the meter is .0.00 to 2.50 mg/l PO4. Does this need to be converted to ppm or is the value shown already in ppm?

 

[Randy Holmes-Farley]

That would be so close to ppm that a conversion wouldn't be needed.

1 mg/L would be ppm in fresh water, but since 1 L of seawater weighs about 1.026 kg, the 1 mg/l = 1 mg/1.026 kg = 0.975 ppm

So a reading of 0.0300 mg/L is really 0.0293 ppm, the difference of which is smaller than the uncertainty of the device.

 

[SPotter]

Thank you for the quick response. I hadnt tested my po4 in a few weeks because all of my sps have been looking better than ever....great pe, color and growth. My po4 had been .03-.05 on the martini for weeks so since my eyes have been saying that everything looks great I didnt bother testing. Well last night I tested and retested and retested and my PO4 is .23 on the martini so I wanted to make sure I didnt need to convert it to ppm like I had to do with the Hanna ULR tester. So my po4 is high but my tank looks great. I will try to bring it down gradually.

 

[Randy Holmes-Farley]

A few tanks naturally do very well at high phosphate, even as high as 1 ppm. In those tanks, algae must be limited by other factors, such as iron, and SPS can do fine.