How to properly check and adjust ppm

Hey guys so my TDS meter came in today. How exactly does ppm work? Do i check before i water then after i water to see how much the plant actually took in? And if to low or high how exactly do I adjust it? Do i just add more water to bring ppms down and more nutes to being up? @Hellraiser @MrPeat @dbrn32 @SKORPION @PurpNGold74

And sorry if im answering my own questions. Im just not sure if the way i think its done is accurate or not and trying to test how much i actually know

All of the above actually… ur first time? U have a myriad of variables n constants to learn.

First test ur tap water. Thats ur baseline.

Then test ur rain water. For :poop:s n giggles.

Maybe test some distilled. Should be under 25 ppms…

Next mix up a nutrient solution. Test that!

Then hopefully its a feed day… or u can pour that out/on grass/in veggies… ud much rather get runoff of water only. Find out how many ppms in your soil. Slowly yet completely water the pot. U want a slow trickle first. Then pour a bit more n catch ur runoff. Test that. Thats kinda ur soil.

U could also get a slurry test for a better look at your topsoil area. Scoop of dirt, distilled water (couple ozs), mix n let sit a few hours. Test that. Thats ur soils slurry.

Point is. Get friendly with ur meter. You wont need to know all those numbers at any given point, but u want to know them eventually so when u check going in, coming out. U can reason it out


U follow your nutrient lines schedule. Usually people cut it in half to start.

Yes more water decreases ppms, but try to take ur time and get it right. Better to aim low
Then high with ppms


The ppm it says is that before or after i water?
Heres a picture of the chart plus im using FFOF

Or should that be the ppm of the water and nutes before i water

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Purps has you covered. :+1::+1::+1:


I believe it. This whole forum has helped grasp so much understanding on things i was before confused or new to. Well appreciated :muscle:t4:


I personally check the water PPM before I add my nutrients. Then I pH up or down after adding the nutrients. Then water. :+1:


So to be sure

  1. Check water ppm
  2. Add nutes (if needed depending on the results of step one)
  3. Adjust ph levels.
  4. Water your plant
  5. Check ppm from run-off
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After add nutes u need to know that ppm too.

Only reason i said check water is to know how much of ur before and after feed ppms is just water.

Check this. My tap is 75 ppms.

I need to add 600ppms of grow big and tiger bloom (or whatever) by the schedule. So after i add the appropriate dashes of nutes, my ppm should read 675. 600 of whatever im supposed to add and 75 of whatevers in my tap.

When i pour it on my soil, it may come out around 800… maybe come out around 1000… no worries. Both are cool.

Next time i add water, itll be 75 ppms clean water. Runoff should fall nicely… be around 500 from the 800… maybe around 7-800 from the 1000…

By the nexttime u feed… if it calls for 600, u pour 675 (adjusted for ur tap) and get the same numbers of runoff? Ur at the sweet spot. Can adjust up a touch nextweek (or keep following ur schedule, they do kinda research their products)


Perfect! Got it. Thanks for the help


Here is an article I found useful. It isn’t a how to but rather what does it mean Runoff pH: Explaining the Bro Science | Curious Cultivations

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I checked my ppm today after water it was 805. @PurpNGold74 I never really learned that part yet. Assuming it’s okay from above statement.

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Have u added anything to the ingoing solution? Or just plain water. Also depends on the stage.


Im 5 week in flower. I add Dyna bloom, pro Tek, and Mag pro

Thats truly not bad. A bit low imo but im not familiar with any of those brands so maybe just fine. Pics of plant?

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Week 5? She doesnt look bad but isnt quite bulking up. I dont see a nutrient issue at all. More like lighting but im sure you know that eh

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Yes I know :unamused: very first grow had no idea anything about lights till I came here. Hopefully real soon I will have enough. I’m going with HLG probably.