Hi cugal, a TDS meter measures Total Dissolved Solids in PPM Parts Per Million. It converts EC electrical conductivity to TDS. If you have a premixed fertilizer or you mix it yourself you will know the NPK ratio so a TDS meter will aid in determining the total concentration of your final solution that you will be feeding your plants. 800-900 PPM is a good measurement to feed pepper plants during the growth stage. For the young ones 300 PPM max.
Hope that helps you out a bit:)

Eric

Thanks Eric! Sooo.............. If I'm mixing a water soluble fertilizer, I should be able to determine it's concentration just by using my TDS meter? I've tested my tap water & it's showing around 450 ppm, so would I need to subtract that number from my final fertilizer solution reading?

Cugal, that's correct. But what you could do is boil that water for a couple minutes, let it cool, then check it. Or let the water sit a few hours and check again. The lower you can get the PPM the better before adding your fertilizer. 450 is pretty high though, you'll want to try to get some of the chlorine off your water.

Thanks ab2008 for keeping me on track! I did notice (on the scale on the back of my meter) that 450 ppm for tap water is very high (500ppm being the EPA's max). I'll start boiling my water!

It might be other things than chlorine, I'm by no means a water expert so don't take what I say as 100% accurate lol. But I'd start there, and see what ya could get it down to. 450 just seems crazy high. Tap water here I test at around 90-110 or so.

Whoa.... 450ppm is way too high. Please get a filter; your plants will thank you.

Eric

Stomach will as well :p

Your TDS meter was correctly calibrated, right?

Many municipalities use Chloramine rather than Chlorine now, and Chloramine is much more stable - in other words, setting water out won't get rid of it; rather, it will increase the concentration marginally.

I second the suggestion of a filter.

Josh

Oh not sure. I know here they still use chlorine, as my father works for the local water utility. I have heard of the use of chloramine though, but wasn't sure exactly how and where it's used more.

Doesn't water that has chloramine in it have almost a blue look to it? I thought I read somewhere that it did, but wasn't sure.

ottwawpepper............. not sure about the calibration part.... My new meter is a very cheap one (TDS EZ by HM Digital). Instructions don't mention calibration & I don't have anything to compare it with.

Yuuup, does appear I need to invest in a water filter!

cugal,

Maybe it's just me but I'd want to make sure my "cheap" TDS meter wasn't 450 ppm off before I invested and $$$'s in a water filtration system. You should be able to get some calibration testing solution where you got your meter.

Just sayin.

Thanks ottawapepper, you may have saved me some money! Calibration testing solution sounds much cheaper than a water filtration system! I'm on it.........

Tried boiling my tap water that was testing 350- 450 ppm out of the faucet & it now tests 650-750 ppm......... How could that be?

water evaporated and left everything else more concentrated

Thanks bberkmor! Makes sense.... Guess my common sense sometimes leaves me stranded......LOL

HM Digital maybe inexpensive but it is a very good meter. HM makes the same meter for other companies like sunleaves. Sunleaves has their name stamped on it and charges twice the price for the same meter.
I'm sure your meter is fine and calibrated properly. An easy way to just check to see if it's functioning properly is to pour some distilled water from a fresh jug into a brand new plastic cup and test it with your meter it should read zero ppm. Don't forget to rinse the probes with distilled water first to remove any possible contaminants.

Eric

Forgot to add: TDS or EC ppm readings greater than zero will vary with temperature.

Eric