PPM and TDS pen question

I was wondering if PPM and TDS pens do the exact same job and can they be used in place of each other?

Basically yes. TDS is "Total Dissolved Solids" and PPM is simply "Parts Per Million". Check out an HM Aqua Pro II. Extremely simple to calibrate and use, stays calibrated a long time for sure and is affordable. Whatever meter or device, buy the calibration solution it requires when you order the device.

I don't order things online so it has to be bought at a local store and I got a TDS meter with my ZeroWater thing. I do already have a PH pen just not a PPM/TDS meter.

mine does ph ec ppm and temp