How to read ppm’s?


Could anyone please explain the readings from a ppm reading ? Where is the sweet spot ? Does the ph effect the ppm reading ? Also, the ppm is only for run off correct ?
Please help, confused


I guess the experts took the night off @JBC13. PPM is Parts Per Million which in simple terms, is a measurement of how much nutrients you have in your water. I have well water so if I measure the PPM of just the water, it’s around 100. When I start feeding my plants nutrients at about week 4 after they sprout, the PPM of my nutrients in the water is around 500 because I use a reduced strength mix of them. By the time I’m at week 8, I’m usually mixing nutrients at 850 to 1100 PPM strength because the plants are growing and demand more nutrients thus higher PPM. Hope that helps explain better


@skgrower Thank You for your help. Checking the ppm is for run off only ? I’m growing in soil. Ph is balanced. So if I check the run off where should the ppm range be for young plants, 4 sets of true leaves. I certainly wish these meters would come with a decent instruction.
Thanks again !


No. Check the ppm of your nutrients mix each time you feed. Not just runoff. Say your feeding a plant 800 PPM nutes and the runoff is 1800, the plant is not taking in most of the nutrients. The soil is. I started out using way too much PPM of nutrients and had all kinds of problems. I learned to pretty much use the recommended nutrients mix and the runoff is the same PPM as what I feed the plants. That’s what I’m shooting for.



Got just the thing for ya…

This is really large so beware…lol
But it explane’s it all. Copy and paste it to your files for future reference.

Knowing What Your Plants Are Eating and How Much They Can Handle
October 20, 2016 by Devin Martinez
One big question growers ask is “Why are my plants suffering even though
I used all the right nutrients, feeding cycles, lighting cycles, and adjusted
temperatures and conditions to their absolute best?”
That’s because their pH and PPM levels are off, making it difficult for your
plants to eat. pH refers to potential of Hydrogen ions in your water, which
will determine if your water is too acidic or has too much alkaline in it.
PPM (parts per million) refers to the concentration of minerals and soluble
matter in your watering solution.
Correct pH and PPM levels are the backbone of any grow, and will be the
difference between a healthy grow and a huge waste of time and money.
pH Levels
Simply put: the right pH level will create an environment where your plants
can absorb nutrients quickly and easily, leading to a better harvest.
Nutrient-rich water is filled with elements that are helpful to your plants.
However, if those elements can be broken down properly those same elements
can harm your plants.
pH levels is important to understand because the right level will determine
the quality of helpful bacteria in your water that help break down elements,
helping the metabolic rate of your plants. How? In two ways:
? When pH levels are too low (pH level of around 5 of lower), heavy
metals like iron and aluminum change and can become toxic to your plants
? If the pH level is too high (pH level of around 6.5 or higher)
elements like calcium and phosphorus can’t be broken down completely, which
will hinder the growth of your plants
This change in properties is due to how acidic your water is or is not.
You’ll want your plants’ nutrients to be a little acidic otherwise they can’t
break down, but too much acidity and your nutrients can become toxic.
So remember: pH too low= toxic to your plants, too high= growth decrease.
That’s why you want to have the perfect level of acidity in your water,
which will be around 5.5-6.0
Typical pH Levels
? 3.5 and below: Root Damage
? 4.0-4.5: Poor Nutrient Uptake
? 5.0-5.4: Good pH Level
? 5.4-5.8: Perfect pH Level
? 6.0-7.0: Acceptable pH Balance
? 7.5-8.0: Poor Nutrient Uptake
? 8.5 and Above: Root Damage

Note: Soil grown plants tend to need a little bit higher of a pH than hydroponics
because soil retains and releases certain elements to your plants at different times.
However, both hydroponic and soil pH levels should stay within the same optimal range
of 5.5-6.0 pH.
PPM Levels
PPM (Parts Per Million) refers to concentration of the particulates in your feeding
From minerals found in tap water to natural elements found in your nutrients, your
job is to make sure that the PPM levels in your water solution are on point so you’re
not under- or over-feeding your plants. While it’s an easy concept to understand on
the surface, it’s a little more complicated when you have to adjust elements.
Now, pH plays a huge factor in PPM levels because even though you may have the correct
PPM reading, some of the particles- and the concentration of those particles- can be
harmful for your plants.
For example, let’s say your plants need to be at a PPM level of 700. You mix your
solution and you get a PPM reading of 700 but your pH is around 4.5. That means that
the majority of the available food for your plants is likely to have lots of heavy
metals in it, which will quickly toxify the plant. You’ll need to adjust the pH level
of your solution to make sure you’re not toxifying your plants.
“But won’t that throw my PPM levels off because you’re adding particles to your feeding
solution?” It can, and that’s what’s so tricky about PPM and pH levels: When you adjust
one you usually have to adjust the other, which can be simple or a huge pain depending
on the water and nutrients you’re feeding your plants.
Common PPM Readings
These readings reflect the PPM your water should have at a given stage of growth
? Seedlings: 100-250 (nutrients aren’t really needed here, hence there’s not a
lot of particles needed)
? First Half of Vegging Cycle: 300-400 (this is usually after you transplant,
which still don’t require many nutrients)
? Second Half of Vegging: 450-700 (you’ll start giving your plants more nutrients
at this stage)
? First Half of Flowering: 750-950 (your plants will be eating more as they grow,
so they’ll be taking in more nutrients)
? Second Half of Flowering: 1000-1600 (this is when your plant’s eating the most,
especially if you give it additives)
? End of Flower, Entering Harvest: As close to 0 as possible (this is when you’ll
be flushing your plants, so you don’t want there to be a lot of particles left over)
Adjusting pH Levels
When it comes to feeding plants there’s two ways of looking at it: homemade or store bought.
Same goes with balancing your pH: you can either purchase a pH buffer from a store or you
can use ingredients you can find around your home or in the grocery store– but both come
with their advantages and disadvantages.
Homemade pH Buffers
? Advantage: If pH levels are low you can use a little citric acid or even white
vinegar to help bring your water’s pH down. When you need to raise your pH levels you
can use a little bit of baking soda in your solution and bring those readings back up.
This will cost you less than picking up a buffering solution.
? Disadvantage: The issue with using these solutions is that they don’t work for
very long. You’ll find yourself having to add a little lemon juice every other day, then
having to use a little baking soda to even things out. Moreover, we’ve also heard of
growers using these ingredients and seeing severe spikes in pH, which if not handled
properly and quickly and bring your grow to a halt.
Premade pH Buffers
? Advantage: Most hydroponic companies out there will have pH buffers, usually
called . They’re much easier to use than citric acid or white vinegar mixes. They’re
designed raise and lower the pH of your water while keeping your water’s pH levels
balanced for longer than it would be without them.
? Disadvantage: As we’ve always mentioned, easier usually means more expensive.
These solutions usually won’t cost you an arm and a leg, but they’re definitely something
you can’t simply make at home and will cost some money.
Adjusting PPM Levels
Before you start adjusting your PPM levels, you’ll first want to make sure your tap water
is ready to feed your plants. That means you’ll want to adjust the PPM of your base water
before you start feeding it to your plantsNow, any time you add anything in to your watering
solution, you’ll be adding more particles in to it, so keep an eye out on your PPM levels at
all times.
? To rid your water of too many particles you can use things like a carbon filter or a
reverse osmosis machine to clean your water. However, many growers agree that most tap water
has helpful minerals (like calcium and magnesium) that actually help plants.
? During and after the vegging stage, your plants will want more out of their feedings
so filtering isn’t really necessary. That’s why we recommend only using filters at the
beginning of the plants life when low PPM readings are needed
? For a quick fix when PPM’s are high just add a bit of fresh water with a good pH
level and watch them drop. Filtered, pH’ed water is great when things get a little too
much in your reservoirs.
? When readings are low it’s usually time to feed your plants. When you add nutrients
to your feeding solution your PPM’s will go back up, and when your PPM’s and pH’s are in balance your plants are going to be happy and healthy
Just remember that these readings need constant adjustment, so if you haven’t been
keeping a close eye on your plant’s PPM and pH levels there’s not better time to start than now.

Citric acid good / bad

Thanks Will. I never really understood the readings as well.


Thank you thank you thank you :slight_smile: i have been struggling with this topic also and going into my 2nd grow i want things to go better than the 1st and the thing was getting me was this!! You have explained it in a way that i actually understand so once again i thank you for making it clearer :slight_smile:


@Wildwest and @Laurap

This is what I like the most of all.
Exactly what Wildwest said in his reply. That put a :grin: on my fase. Awesome for the both of you and anyone else that it mite help out.


Im glad i could help even if only with a little smile :slight_smile:

You have helped me loads over my time on here and i thank you and everyone else who has made it possible :slight_smile:


P.s im a maam :wink:



This happens to much not knowing if we’re talking to a male or female.
I started a list of whos who on here so tat I don’t keep making the same mistake. I think I will bring the up with the front office. Maybe they can come up with a way to let members know the gender of who there talking with.


@garrigan65 its no biggie on my part just thought i would point it out lol

Altho that would be a good idea to be able to have something to specify gender :slight_smile: i thought i was talking to a guy the other day but turns out he is a she :see_no_evil:


Great thread! Very informative. Thanks @garrigan65!


Will, once again many thanks for all your time
P.S. gonna do that crushing of my beautiful buds. Need some help & support please!


Ok. Ready when you are