Hi!
Your pool guy is full of it. He just wants to sell you expensive phosphate remover, regularly.

Ditching the N2 is a good idea.

You need to spend $50-$80 on a good test kit. We recommend the Taylor Technologies K-2006 or K-2006C. You can get the best price by clicking on the link in either WaterMom's or PoolDoc's signature.
Gotta run. More later.