Does PPM matter?

I've seen a few grows on here that said they dont even know there PPM and the meters are pricey will my plants grow if i dont do anything to it?

PPM meters matter with larger Hydro grows. There is a LOT more water flowing, and many many more plants drinking up all your nutes. With a small personal grow, don't buy the meter, just change your res water once every week or so and you should be good. Also, if you use the fox farm nute trio and its feeding schedule (http://www.4hydroponics.com/nutrients/Mnl/foxFarmHydro.pdf) your ppm and ph will stay within desireable levels.

Thanks alot I thought I was stuck buying that expensive meter +++rep

you can find sub 20$ usd ppm meters on ebay. they arent waterproof or the greatest but for the price theyre worth the money imho.