Tap water and PPM

This is my first grow and I'm using tap water in my hydro setup. My question is, Do you subtract the PPM of the plain tap water from the PPM of the water after adding nutes? Like for instance, if I was shooting for 700 PPM nute solution and my tap water comes out at 300, do I go with 1000 PPM solution? Another thing I was wondering was all those PPM guidelines, are they counting the PPM of the water as well or is that the PPM after subtracting that of the water?

bump......

you do subtract the PPM of your tap water from the total. Also, you should 1/2 all the nute recommendations if you are using hard tap water (over 2-250 PPM).

Are you using G.H. hard water micro? That is the only hard water specific nutrient i know of...

here is a very good thread to read from Earl regarding pH/PPM and feeding in a hydro system...
CC Hydro 101 by Earl - Cannabis Culture Forums

SuperSmoker420 said:

This is my first grow and I'm using tap water in my hydro setup. My question is, Do you subtract the PPM of the plain tap water from the PPM of the water after adding nutes? Like for instance, if I was shooting for 700 PPM nute solution and my tap water comes out at 300, do I go with 1000 PPM solution? Another thing I was wondering was all those PPM guidelines, are they counting the PPM of the water as well or is that the PPM after subtracting that of the water?

Click to expand...

they("ppm guidlines")are calculating ppm using water used from RO(reverse osmosis means usually less than 30ppm) machines.

if your not using RO water, you dont want to use full strength nutes!!

yes, if you want to find out how much nutes you are using you want to subtract your tap water ppm from your final reading. when it comes to noobs growing pot, remember less is more when it comes to nutes.

when going with soil, use ferts every other watering, and flush once a month or so.

good luck

email beat me to it.. i thought i was going to be the first poster

i wrote more some good info too hehe

In my city, at the public library. You can get an annual "city water report"

It will tell you all the amounts of elements in your tap water.

We have 100ppm Na in our tap water, you don't want to give that to you plants.

my tap water is at 150ish is that bad?

my opinion is that is pretty low PPM for tap water and while not ideal, i doubt you'd have any problems growing some prime bud provided your strain isn't overly nutrient sensitive and you feed with a light hand.