New by totally confused by various phosphate tests

[Dub]

I started out using API REEF MASTER TEST KIT for phosphate and had difficulty matching the resulting color to the color chart. I finally decided my tank had .5 ppm phosphate. According to most articles on reef parameters it should be near .03 ppm. Before taking corrective action I decided to use a Hanna ULP kit to obtain a digital result. This gave a reading of 155 ppb which is .155 ppm phosphorus. There is a huge difference difference between .155 ppm and .5ppm then I noticed one measured phosphate and the other measures phosphorus. Are these two different measurements and if so can you convert one to the other? If not, is it normal for 2 kits to offer up results this far apart. Finally both readings are far above the recommended level of .03ppm and this being a 2 month old system of 43g what should be done? I do have a small Refugium, protein skimmer and bio rock with live rock. I also use RO/DI water, have used Fritz RPM salt at 1.025 (recently switched to Red Sea Coral) and have been doing weekly 11% water changes. Thanks for any opinions.

 

[Quietman]

They are in agreement...phosphorus to phosphate is x3.066 then divide by 1000 to get ppm.

So...155ppb x 3.066 = 475ppb / 1000 = .475 ppm. (I assume you meant 155 ppb as that's what the Hanna ULP measures)

High phosphates are frequently due to feeding more than required.

 

[Dub]

Thank you

 

[Larry L]

They are in agreement...phosphorus to phosphate is x3.066 then divide by 1000 to get ppm.

So...155ppb x 3.066 = 475ppb / 1000 = .475 ppm. (I assume you meant 155 ppb as that's what the Hanna ULP measures)

Agree, that's the correct math. I have a calculator that does the math for you, and also give you the possible range of actual phosphates for your reading based on the manufacturer's accuracy specs: http://larryl.emailplus.org/fish/test-kit-calculators.html

 

[Quietman]

Agree, that's the correct math. I have a calculator that does the math for you, and also give you the possible range of actual phosphates for your reading based on the manufacturer's accuracy specs: http://larryl.emailplus.org/fish/test-kit-calculators.html

Slick little calculator....really like the ranges displayed