Basic PPM concept ?

"Let say you have a PPM of 550 and it drops down to 500. Does that mean the plants ate the other 50 ppms of nutes. How would that effect the PH - would it go up?"

As the plants "feed" the PPMs will rise because the nutrient content becomes more concentrated. Sounds strange ... but remember, the plants are using water too.

"And if you bring the PH back down again, does the PPM go back up?"

No, because PPM and PH are two different things. The PPM is the parts per million of solids in the solution. The PH measures the acididity of the solution.

The PH will rise and fall with time. As long as it doesn't get too low, say under 5.0, or too high, say over 6.1, your fine. In fact, a little swing is just fine as the plant will take up different amounts of certain nutes as the PH swings. Ideally, keep the PH between 5.4 and 5.8. Unless you're growing in soil. In that case, a PH of 7.0 is fine.

Vi

Quick question, I just changed my water 4 gallons and then added ph down only. I checked the water and it say ppm 1100. I have not added the nuets yet?
My water is 250 ppm. Did this ph down add the ppm's?
thanks

LMAO

hobbyking when you check that "1100 ppm" water did you stir it first before u checked the water for the PH?

yes I did and after I added the ph down.
thanks

dont know why it went from 250-1100 in ppm by adding ph down. It shouldn't even be rising over 10 ppm when u add ph down. what kind of ph down are you using?

General Hydroponics PH Down.
I took a fresh gallon of water (tap water sitting for a couple of days) and had a 252 ppm.
After I added 1 tablespoon of PH Down to the gallon it has a ppm 638.
I am trying to search out what it might be this General Hydroponics PH Down could cause this. I wondering if it needs to react with Nuets?
I do not know
Thanks again

Take you original water ppm.Now lets say your nutes call for being 1200 ppm add nutes to your water until it reads 1452 or 1400 to make it easy.So basically you deduct the water ph then adjust the ph after

thats really strange i use gh ph down also and i don't even get a noticible amount of rising ppm. What about your EC is it rising also along with the ppm? that 250ppm tap water isn't that hard, mines is at 200 sometimes i see like 190.

Wait a min i just reread somehting, you said 1 tablespoon per gal? Thats alot of ph down to use. I have a tap water of 200ppm and 7.9ph, i use 1teaspon per gal and it brings me down to 5.7 w/nutes added as buffer.

So 1 "tablespoon" is way too much to be adding to a gal.

hey you got something, Thanks i will do some testing and get back.
Thanks again

I took 1 gallon water at 282 ppm. Added 1 teaspoon of PH down and waited awhile and mixed it up good and 423 ppm.
I guess I will add that to the two part bloom nutes. So the 2 part says on each gallon 1200 ppm. Do I add 1200 + 1200 + 423 for my target ppm?
I am just learning and had one plant go fold up and go away.
Thanks

also when you are growing in really hot temps, your ppm will rise quicker, because the plants are using more water. If you are growing in cooler temps., sometimes your ppm will go down, because they use more nutes and slightly less water.