Honestly, if you're tight on cash, please don't keep throwing small money at bad meters; small money adds up in time. Snag yourself an old-skool pH liquid/litmus kit - they're highly reliable AND cheap. As for PPM, let me know what type of system and nutes; even though I have a very nice meter, I am following General Hydro's website nutrient calculator to the T and never actually need to read it. Good luck.