Insane NO3... Is it the API kit?

Lately I've been having repeated problems with my NO3 tests by API. I am using these same tubes to test the levels in a batch of curing liverock. I have had to test, rinse tube, and retest. But today that didn't help for a more accurate reading... The exp. date is 2017.



So 9/8, I did a water change in my 30g. I managed to damage my long polyp sarco, by sucking it into my little siphon trying to clean up :doh:



I took levels the day before and aged my SW for 24 hours:



NO3 - 20

NO2 - 0

NH - 0

pH - 8.2

PO4 - 0.5 (slowly getting this down)

Ca2 - 300

KH - 10

SG - 1.022 (raised slowly)

Temp - 82'



After my adjustments, I placed the sarco back in its spot and also added a small amount of carbon to the tank in a media bag to prevent any chemicals from harming anything (esp. my euphyllia).



Today (I try to test weekly), I cannot believe what I'm seeing...



NO3 - 80-160 (tested 3 times)

NO2 - 0

NH - 0

pH - 8.2

PO4 - 0.25

Ca2 - 400

KH - 13

SG - 1.023

Temp - 82'



Should I chalk this up to a crappy test, or is this coming from my sarcophyton? It's polyps have been closed in the middle because it got torn. Everything else looks perfectly complacent... Either way, I am going to do a 5 gal. water change and plan on getting a new test kit...