Live phytoplankton and PO4 testing

[Reef Jedi]

Hey!

I’m a little confused and need some help as I’m newer to using live phytoplankton. I recently did a test yesterday for the first time in 6 months of no3 and po4. No3 was 33ppm but po4 was .3. I was surprised to see po4 that high and proceeded to do a 40% wc last night. After the wc I added a very small splash of phyto about 20ml. Today I tested to see what levels I was left with and no3 is 24.1 and po4 was .411. I figured something had to be wrong with my test so I put a new battery in just incase and re ran it. The second result was po4 at .392. All tests are ran with Hanna checkers.

I would have figured the w/c would have reduced that number by about 40% however it did not. The no3 reacted as expected with the w/c. So the only thing I can think of is maybe the algae barn live phytoplankton is adding po4 back in?

I’m not too adverse with po4 and live phytoplankton so I really need others with this experience to chime in.

Here’s some tank shots

Other levels incase I’m asked:
Temp: 78
Salt: 35ppm
Alk: 8.3
CA: 455
Mg: 1350
Ph - currently 8.39

 

[Dan_P]

Try testing the concentration of PO4 in the phyto additive. Measure the PO4 in a sample of aquarium water before and after adding the phyto

 

[Submerge]

Can you measure phos in phyto on Hanna? Seems the color of the phyto would render any result useless. Or at least skewed.