Forget about the N and P... you have larger problems. ...and do not ever worry about P unless you have a Hannah Ultra Low and can measure in parts per BILLION. Unless you are using a ton of Lan Chloride, organic carbon or GFO, then you have some... and some is enough... for now.
N and P worry should be about fine tuning micro level and not the macro. I know that BRS videos and the interwebs has everybody worried about it, but figure out the big stuff first, get good at it and then worry about the micro. Lights, filtration, testing, stability, skimming, reliability (of the reef and the reefer) at the macro level all need to get figured out first. Just pretend that you do not have a N or P test kit until then.