Use the testkit link in my blue signature bar, above. A link to the correct phosphate kit is found in the phosphate remover thread, linked above, but here it is again:
Taylor Technologies K-1106 Phosphate test kit
Hach Company 562227 Phosphate Test Kit (Aqua-Check)

Kem-Tek phosphate remover (most phosphate removed per $ spent)

I'll go ahead and post the K2006 links, too:
K2006A
K2006C